Securities - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified			3 Months Ended
	Mar. 31, 2014 Securities	Dec. 31, 2013 Securities	Mar. 31, 2014 Four Structured Pool Trust Securities [Member] Securities	Mar. 31, 2013 Four Structured Pool Trust Securities [Member]	Mar. 31, 2014 Pooled Trust Preferred [Member]	Dec. 31, 2013 Pooled Trust Preferred [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities holdings	0
Shareholders' equity percentage	10.00%
Number of Pooled Trust Securities			1
Amortized Cost	$ 692,949	$ 697,738			$ 800	$ 800
Fair Value	687,862	685,991			798	661
Other than temporary impairment recognized in earnings for available for sale securities			0	0
Number of structured pooled trust preferred securities deemed to be other-than-temporarily impaired	4	4
Securities	$ 339,490	$ 353,102