Parent Company Condensed Financial Information - Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Financial Information [Line Items]
Cash	$ 108,356	$ 337,711	$ 270,526	$ 108,196
Other assets	103,026	120,395
Total Assets	4,533,190	4,526,702
Other liabilities	48,300	88,550
Total Liabilities	3,961,884	3,989,280
Total Shareholders' Equity	571,306	537,422	490,526	578,665
Total Liabilities and Shareholders' Equity	4,533,190	4,526,702
Parent Company [Member]
Condensed Financial Information [Line Items]
Cash	14,852	12,202	13,684	110,889
Bank subsidiary	553,825	523,664
Nonbank subsidiaries	19,561	19,934
Other assets	4,441	3,129
Total Assets	592,679	558,929
Long-term debt	20,619	20,619
Other liabilities	754	888
Total Liabilities	21,373	21,507
Total Shareholders' Equity	571,306	537,422
Total Liabilities and Shareholders' Equity	$ 592,679	$ 558,929