18.COMMITMENTS AND CONTINGENCIES

Leases

The Company is obligated under various non-cancelable operating leases for land, office space, equipment and site leases that expire at various times through July 2114. In addition, the Company is obligated under various non-cancelable capital leases for vehicles that expire at various times through July 2018.

The annual minimum lease payments under non-cancelable operating and capital leases in effect as of December 31, 2014 are as follows (in thousands):



For the year ended December 31,	Capital Leases		Operating Leases
2015	$	1,652	$	135,563
2016		975		136,675
2017		499		138,640
2018		148		140,209
2019		—		140,620
Thereafter		—
Total minimum lease payments		3,274
Less: amount representing interest		(169)
Present value of future payments		3,105
Less: current obligations		(1,741)
Long-term obligations	$	1,364

Future minimum rental payments under noncancelable ground leases include payments for certain renewal periods at the Company’s option because failure to renew could result in a loss of the applicable tower and related revenue from tenant leases, thereby making it reasonably assured that the Company will renew the lease. The majority of operating leases provide for renewal at varying escalations. Fixed rate escalations have been included in the table disclosed above.

Rent expense for operating leases was $223.4 million, $196.3 million and $133.1 million for the years ended December 31, 2014, 2013 and 2012, respectively. In addition, certain of the Company’s leases include contingent rent provisions which provide for the lessor to receive additional rent upon the attainment of certain tower operating results and/or lease-up. Contingent rent expense for the years ended December 31, 2014, 2013 and 2012 was $23.3 million, $20.3 million and $16.1 million, respectively.

Tenant Leases

The annual minimum tower lease income to be received for tower space and antenna rental under non-cancelable operating leases in effect as of December 31, 2014 is as follows:



For the year ended December 31,	(in thousands)
2015	$	1,220,266
2016		1,081,408
2017		956,211
2018		806,190
2019		611,057

The Company’s tenant leases provide for annual escalations and multiple renewal periods, at the tenant’s option. The tenant rental payments disclosed in the table above do not assume exercise of tenant renewal options, however, fixed rate escalations have been included.

Litigation

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 that may be incurred, management believes the resolution of such uncertainties and the incurrence of such costs will not have a material adverse effect on the Company’s consolidated financial position, results of operations or liquidity.

Contingent Purchase Obligations

From time to time, the Company agrees to pay additional consideration (or earnouts) for acquisitions if the towers or businesses that are acquired meet or exceed certain performance targets in the one to three years after they have been acquired. For the years ended December 31, 2014, 2013, and 2012 certain earnings targets associated with the acquired towers were achieved, and therefore, the Company paid in cash $18.7 million, $9.3 million, and $5.9 million, respectively. As of December 31, 2014, the Company’s estimate of its potential obligation if the performance targets contained in various acquisition agreements were met was $15.1 million which the Company recorded in accrued expenses. The maximum potential obligation related to the performance targets was $23.1 million and $42.1 million as of December 31, 2014 and 2013, respectively.