Fair Values of Assets and Liabilities - Schedule of Changes in Level 3 Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 25,932	$ 34,004	$ 24,793	$ 37,812
Total gains or losses included in earnings	257	1,102	383	2,409
Total gains or losses included in other comprehensive income	3,292	(688)	5,683	1,580
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	3,779	9,172	(20,518)	(15,981)
Settlements	1,935	2,034	(3,187)	(3,069)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0
Balance, end of period	27,289	23,212	27,289	23,212
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	3,522		20,135	461
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	24,512	24,508	23,373	22,980
Total gains or losses included in earnings	0	0	0	0
Total gains or losses included in other comprehensive income	3,292	(688)	5,683	1,580
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	1,935	2,028	(3,187)	(2,768)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0
Balance, end of period	25,869	21,792	25,869	21,792
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0		0	0
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	1,420	1,420	1,420	1,420
Total gains or losses included in earnings	0	0	0	0
Total gains or losses included in other comprehensive income	0	0	0	0
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0
Balance, end of period	1,420	1,420	1,420	1,420
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0		0	0
Loans Held For Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	8,076	0	13,412
Total gains or losses included in earnings	257	1,102	383	2,870
Total gains or losses included in other comprehensive income	0	0	0	0
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	3,779	9,172	(20,518)	(15,981)
Settlements	0	6	0	(301)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0
Balance, end of period	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	3,522		20,135	0
Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	0	0	0
Total gains or losses included in earnings	0	0	0	(461)
Total gains or losses included in other comprehensive income	0	0	0	0
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0
Balance, end of period	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	$ 0		$ 0	$ 461