Condensed Financial Information (Parent Company Only) - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed balance sheets:
Cash and cash equivalents	$ 780,457	$ 798,670
Investment in subsidiaries, at equity:
Other assets	78,074	73,495
Total assets	8,728,196	8,609,936
Subordinated debentures held by subsidiary trusts	82,477	82,477
Total liabilities	7,777,703	7,701,012
Stockholders’ equity	950,493	908,924	$ 801,581	$ 751,186
Total liabilities and stockholders’ equity	8,728,196	8,609,936
Parent Company
Condensed balance sheets:
Cash and cash equivalents	55,162	65,483
Investment in subsidiaries, at equity:
Equity method investments	977,221	938,799
Advances from subsidiaries, net	6,257	4,337
Other assets	39,668	29,335
Total assets	1,078,308	1,037,954
Other liabilities	25,338	26,553
Long-term debt	20,000	20,000
Subordinated debentures held by subsidiary trusts	82,477	82,477
Total liabilities	127,815	129,030
Stockholders’ equity	950,493	908,924
Total liabilities and stockholders’ equity	1,078,308	1,037,954
Bank subsidiary
Investment in subsidiaries, at equity:
Equity method investments	975,236	936,817
Nonbank subsidiaries
Investment in subsidiaries, at equity:
Equity method investments	$ 1,985	$ 1,982