Schedule of Financial Instruments Having Difference Between Carrying Amount and Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Investment in direct financing lease, Carrying Amount	$ 7,466	$ 9,233
Note receivable from APM, Carrying Amount	4,831	4,819
Debt, Carrying Amount	(1,205,000)	(1,111,545)
Investment in direct financing lease, Fair Value	8,609	10,852
Note receivable from APM, Fair Value	9,006	8,678
Debt, Fair Value	$ (1,179,375)	$ (1,152,550)