Commitments and Contingencies

12 Months Ended

Dec. 31, 2011

Commitments and Contingencies [Abstract]

Commitments and Contingencies

Commitments and Contingencies

The Company is involved in various claims, lawsuits and proceedings arising in the ordinary course of business. While there are uncertainties inherent in the ultimate outcome of such matters, and it is impossible to presently determine the ultimate costs or losses that may be incurred, if any, management believes the resolution of such uncertainties and the incurrence of such costs should not have a material adverse effect on the Company's consolidated financial position or results of operations.

Asset Retirement Obligations

Pursuant to its ground lease and easement agreements, the Company has the obligation to perform certain asset retirement activities, including requirements upon lease and easement termination to remove wireless infrastructure or remediate the land upon which its wireless infrastructure resides. Accretion expense related to liabilities for retirement obligations amounted to $5.6 million, $5.3 million and $4.9 million for the years ended December 31, 2011, 2010 and 2009, respectively. As of December 31, 2011 and 2010, liabilities for retirement obligations were $68.5 million and $63.8 million, respectively, representing the net present value of the estimated expected future cash outlay. As of December 31, 2011, the estimated undiscounted future cash outlay for asset retirement obligations was approximately $1.4 billion. See note 2.

Property Tax Commitments

The Company is obligated to pay, or reimburse others for, property taxes related to the Company's wireless infrastructure pursuant to operating leases with landlords and other contractual agreements. The property taxes for the year ended December 31, 2012 and future periods are contingent upon new assessments of the wireless infrastructure and the Company's appeals of assessments. The Company has an obligation to reimburse Sprint Nextel ("Sprint") for property taxes it pays on the Company's behalf related to certain towers the Company leases from Sprint. The Company paid $15.4 million for the year ended December 31, 2011 and expects to pay $15.8 million for the year ended December 31, 2012. The amount per tower to be paid to Sprint increases by 3% each successive year through 2037, the expiration of the lease term.

Letters of Credit

The Company has issued letters of credit to various landlords, insurers and other parties in connection with certain contingent retirement obligations under various tower land interest leases and certain other contractual obligations. The letters of credit were issued through the Company's lenders in amounts aggregating $10.8 million and expire on various dates through December 2012.

Operating Lease Commitments

See note 15 for a discussion of the operating lease commitments.