Derivative Instruments and Hedging Activities - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	May 14, 2013 Swap	Jun. 30, 2014 Interest Rate Swaps [Member] Swap	May 14, 2013 Interest Rate Swaps [Member] Swap	Aug. 23, 2012 Interest Rate Swaps [Member] Swap	Jun. 30, 2014 Not Designated as Hedge Accounting Relationships [Member]	Dec. 31, 2013 Not Designated as Hedge Accounting Relationships [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives outstanding							$ 0	$ 0
Notional amount of interest rate swap (In USD)				1,000,000,000	550,000,000	550,000,000
Number of outstanding interest rate derivatives				3	2	2
Number of restructured interest rate swaps			2
Reclassified as an increase to interest expense	2,914,000	2,914,000
Tax benefit on unrealized loss on derivatives	(537,000)	(660,000)
Termination value of derivatives in net liability position	1,688,000	1,688,000
Collateral posted relating to credit risk-related contingent features	$ 0	$ 0