Schedule of Financial Instruments Having Difference Between Carrying Amount and Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Investment in direct financing lease, Carrying Amount	$ 3,223	$ 5,473
Note receivable from APM, Carrying Amount	3,504	3,677
Debt, Carrying Amount	(1,464,000)	(1,200,000)
Investment in direct financing lease, Fair Value	3,408	6,048
Note receivable from APM, Fair Value	5,864	6,539
Debt, Fair Value	$ (1,452,719)	$ (1,179,625)