Condensed Parent Company Financial Statements (Detail) - Statements of Financial Condition (Parent Company Only) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets
Cash and due from banks	$ 381,202	$ 606,262	$ 587,241	$ 716,266
Goodwill	319,007	310,589	264,062	265,477
Other assets	174,560	190,912
Total assets	9,732,676	9,445,139
Liabilities and Stockholders’ Equity
Senior and subordinated debt	201,208	200,869
Accrued interest payable and other liabilities	122,366	117,743
Stockholders' equity	1,146,268	1,100,775	1,001,442	940,893
Total liabilities and stockholders' equity	9,732,676	9,445,139
Parent Company
Assets
Cash and due from banks	119,693	43,546	$ 13,071	$ 20,970
Investments in and advances to subsidiaries	1,184,900	1,211,244
Goodwill	18,216	13,625
Other assets	54,394	79,468
Total assets	1,377,203	1,347,883
Liabilities and Stockholders’ Equity
Senior and subordinated debt	201,208	200,869
Accrued interest payable and other liabilities	29,727	46,239
Stockholders' equity	1,146,268	1,100,775
Total liabilities and stockholders' equity	$ 1,377,203	$ 1,347,883