Income Taxes - Deferred Income Taxes Related to Temporary Differences between Tax Bases of Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax liabilities:
Accelerated depreciation	$ 293,141	$ 286,618
Prepaid costs currently deductible	6,572	6,997
Other	5,747	5,034
Total deferred tax liabilities	305,460	298,649
Deferred tax assets:
Accrued costs not yet deductible	9,785	8,638
Allowance for doubtful accounts	809	804
Net operating loss carry forwards		577
Deferred revenues	965	1,945
Share-based compensation	1,882	3,334
Total deferred tax assets, net of valuation allowance of $0.7 million in 2016	13,441	15,298
Deferred income taxes, net	$ 292,019	$ 283,351