Fair Value Measurements - Additional Information about Assets Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 33,749	$ 32,565
Total gains (losses) - realized/unrealized, Included in earnings	13,766	78
Total gains (losses) - realized/unrealized, Included in other comprehensive income	5,640	6,705
Accretion included in earnings	659	3,176
Purchases
Issuances		38
Sales/redemptions	(51,527)	(1,033)
Settlements	(233)	(1,698)
Transfers from Level 3		(6,082)
Transfers into Level 3
Balance at end of period	2,054	33,749
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	31,595	22,456
Total gains (losses) - realized/unrealized, Included in earnings	13,766
Total gains (losses) - realized/unrealized, Included in other comprehensive income	5,608	6,701
Accretion included in earnings	657	3,160
Purchases
Issuances		38
Sales/redemptions	(51,527)
Settlements	(99)	(760)
Transfers into Level 3
Balance at end of period		31,595
Other Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period		6,892
Total gains (losses) - realized/unrealized, Included in earnings		78
Total gains (losses) - realized/unrealized, Included in other comprehensive income		21
Accretion included in earnings		4
Purchases
Sales/redemptions		(1,033)
Transfers from Level 3		(5,962)
Transfers into Level 3
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	410	512
Total gains (losses) - realized/unrealized, Included in other comprehensive income	33	18
Purchases
Transfers from Level 3		(120)
Transfers into Level 3
Balance at end of period	443	410
Residential Non-Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	1,744	2,705
Total gains (losses) - realized/unrealized, Included in other comprehensive income	(1)	(35)
Accretion included in earnings	2	12
Purchases
Settlements	(134)	(938)
Transfers into Level 3
Balance at end of period	$ 1,611	$ 1,744