Summary of Significant Accounting Policies (Additional Cash Flow Information) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Cash paid for interest	$ 12,982	$ 14,705	$ 22,449
Cash paid for income tax	57,086	62,976	49,514
Unsettled purchases of securities	2,998	0	16,241
Loans foreclosed and transferred to other real estate owned and foreclosed assets	933	4,363	6,870
Premises and equipment transferred to other real estate owned and foreclosed assets	0	1,740	0
Loans to facilitate the sale of other real estate owned	20	102	678
Deferred gain on sale of building and parking garage	$ 0	$ 0	$ 768