6. Commitments and contingencies: Capital leases fiber lease agreements The Company has entered into lease agreements with numerous providers of dark fiber primarily under 15-20 year IRUs typically with additional renewal terms. Once the Company has accepted the related fiber route, leases that meet the criteria for treatment as capital leases are recorded as a capital lease obligation and an IRU asset. The interest rate used in determining the present value of the aggregate future minimum lease payments is determined by adding a premium to the US treasury interest rate for the lease term. The future minimum payments under these agreements are as follows (in thousands): For the year ending December 31, 2014 $ 28,965 2015 22,584 2016 21,714 2017 21,663 2018 21,592 Thereafter 246,032 ? ? ? ? ? Total minimum lease obligations 362,550 Less amounts representing interest (200,771 ) ? ? ? ? ? Present value of minimum lease obligations 161,779 Current maturities (9,252 ) ? ? ? ? ? Capital lease obligations, net of current maturities $ 152,527 ? ? ? ? ? ? ? ? ? ? Release of lease obligation In the year ended December 31, 2011, the requirements for extinguishment were met and the Company was released from an obligation under an IRU capital lease obligation totaling $2.7 million resulting in a gain. The IRU asset related to this obligation had been fully impaired in 2008 when it was determined that the IRU asset was no longer in use. Current and potential litigation In accordance with the accounting guidance for contingencies, the Company accrues its estimate of a contingent liability when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Where it is probable that a liability has been incurred and there is a range of expected loss for which no amount in the range is more likely than any other amount, the Company accrues at the low end of the range. The Company reviews its accruals at least quarterly and adjusts them to reflect the impact of negotiations, settlemen