debt:

Debt Capacity

We have available lines of credit and revolving credit agreements with a group of banks and other financial intermediaries. We maintain cash and cash equivalent balances and short-term investments in excess of our commercial paper and other short-term borrowings. As of December 31, 2012, we had access to $9.1 billion of lines of credit, of which $2.0 billion expire within one year. Of these lines of credit, $8.4 billion are unused, of which our lenders have committed to loan us $7.1 billion at our request. Also, $7.0 billion of our unused lines of credit, all of which expire in 2016, may be used to support our commercial paper borrowings.

In December 2012, Zoetis entered into a revolving credit agreement providing for a five-year $1.0 billion senior unsecured revolving credit facility, which became effective in February 2013 and expires in December 2017.

See "Subsequent Events" above for information about a January 2013 Zoetis debt offering and the Zoetis commercial paper program.

Global Economic Conditions

The challenging economic environment has not had, nor do we anticipate it will have, a significant impact on our liquidity. Due to our significant operating cash flows, financial assets, access to capital markets and available lines of credit and revolving credit agreements, we continue to believe that we have the ability to meet our liquidity needs for the foreseeable future. As markets change, we continue to monitor our liquidity position. There can be no assurance that the challenging economic environment or a further economic downturn would not impact our ability to obtain financing in the future.

  Contractual Obligations

The above table excludes amounts for potential milestone payments under collaboration, licensing or other arrangements, unless the payments are deemed reasonably likely to occur. Payments under these agreements generally become due and payable only upon the achievement of certain development, regulatory and/or commercialization milestones, which may span several years and which may never occur.

In 2013, we expect to spend approximately $1.5 billion on property, plant and equipment. Planned capital spending mostly represents investment to maintain existing facilities and capacity. We rely largely on operating cash flows to fund our capital investment needs. Due to our significant operating cash flows, we believe we have the ability to meet our capital investment needs and anticipate no delays to planned capital expenditures.

See "Subsequent Events" above for information about a January 2013 Zoetis debt offering. If we were to incorporate the 2013 Zoetis debt offering into our contractual obligations table above, total payments due would increase by $5.8 billion, representing expected principal and interest obligations of $223 million in 2013 through 2014, $629 million in 2015 through 2016 and $4.9 billion thereafter.

Off-Balance Sheet Arrangements

In the ordinary course of business and in connection with the sale of assets and businesses, we often indemnify our counterparties against certain liabilities that may arise in connection with a transaction or that are related to activities