Derivative Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2016	Dec. 31, 2014
Derivative [Line Items]
Interest Expense	$ (1,359)	$ (1,381)	$ (2,718)	$ (2,742)
Fair value of interest rate swap agreements	14,892		14,892			$ 13,341
Net termination cost	14,900		14,900
Interest Expense [Member]
Derivative [Line Items]
Interest Expense	1,400	$ 1,400	2,700	$ 2,700
Scenario, Forecast [Member]
Derivative [Line Items]
Estimated payments to be made under interest rate swaps					$ 5,400
Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount of variable rate debt swapped	$ 325,000		$ 325,000