Income Taxes - Deferred Income Taxes Related to Temporary Differences between Tax Bases of Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax liabilities:
Accelerated depreciation	$ 286,618	$ 272,496
Prepaid costs currently deductible	6,997	6,358
Other	5,034	4,404
Total deferred tax liabilities	298,649	283,258
Deferred tax assets:
Accrued costs not yet deductible	8,638	7,463
Allowance for doubtful accounts	804	788
Net operating loss carry forwards and credits	577	302
Deferred revenues	1,945	1,132
Share-based compensation	3,334	4,671
Total deferred tax assets	15,298	14,356
Deferred income taxes, net	$ 283,351	$ 268,902