Revenue Recognition Contractual rental revenue is reported on a straight-line basis over the terms of the respective leases. The impact of the straight-line rent adjustment increased revenue by approximately $77.6 million , $77.0 million and $85.1 million for the years ended December 31, 2012 , 2011 and 2010 , respectively, as the revenue recorded exceeded amounts billed. Accrued rental income, as reported on the Consolidated Balance Sheets, represents cumulative rental income earned in excess of rent payments received pursuant to the terms of the individual lease agreements. The Company maintains an allowance against accrued rental income for future potential tenant credit losses. The credit assessment is based on the estimated accrued rental income that is recoverable over the term of the lease. The Company also maintains an allowance for doubtful accounts for estimated losses resulting from the inability of tenants to make required rent payments. The computation of this allowance is based on the tenants  payment history and current credit status, as well as certain industry or geographic specific credit considerations. If the Company s estimates of collectability differ from the cash received, then the timing and amount of the Company s reported revenue could be impacted. The credit risk is mitigated by the high quality of the Company s existing tenant base, reviews of prospective tenants  risk profiles prior to lease execution and consistent monitoring of the Company s portfolio to identify potential problem tenants. In accordance with ASC 805 (formerly SFAS No. 141(R)), the Company recognizes rental revenue of acquired in-place  above-  and  below-market  leases at their fair values over the terms of the respective leases. The impact of the acquired in-place  above-  and  below-market  leases increased revenue by approximately $14.6 million , $10.8 million and $2.4 million for the years ended December 31, 2012 , 2011 and 2010 , respectively. The following table summarizes the scheduled amortization of the Co