Effect of Derivative Instruments on Consolidated Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) or Gain Recognized in OCI on Derivative (Effective Portion)	$ 1,804	$ (7,403)
Amount of Loss Reclassified from Accumulated OCI into Income (Effective Portion)	(1,791)	(3,085)	$ (3,983)	$ (6,810)
(Loss) Gain on Cash Flow Hedge Ineffectiveness, Net	(12)	(59)	(73)	(63)
Designated as Hedging Instrument [Member] | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Loss Reclassified from Accumulated OCI into Income (Effective Portion)	(1,791)	(3,085)	3,983	6,810
(Loss) Gain on Cash Flow Hedge Ineffectiveness, Net	(12)	(59)	(73)	(63)
Designated as Hedging Instrument [Member] | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) or Gain Recognized in OCI on Derivative (Effective Portion)	1,804	(7,403)	(2,543)	(8,400)
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, (Loss) Gain Recognized in Income, Net	0	(59)	(3)	(128)
Not Designated as Hedging Instrument [Member] | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, (Loss) Gain Recognized in Income, Net	$ 0	$ (59)	$ (3)	$ (128)