Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred Income Tax Assets And Liabilities [Line Items]
Asset reserves and liabilities not yet deductible for tax	$ 29,198	$ 28,589
Tax over book basis of certain assets	866	893
Net operating loss and tax credit carryforwards	5,487	5,287
Intangible contract value	2,570	2,717
Noncurrent deferred tax assets, Other	346	460
Total noncurrent deferred tax assets	38,467	37,946
Less valuation allowance	(3,436)	(3,780)
Total noncurrent deferred tax assets	35,031	34,166
Book over tax basis of certain assets	(9,386)	(15,238)
Intangible lease value	(8,368)	(8,862)
Deferred tax liabilities, other	(3,542)	(242)
Total noncurrent deferred tax liabilities	(21,296)	(24,342)
Non-current deferred tax assets	$ 13,735	$ 9,824