Parent Company (Schedule of Condensed Financial Statements-Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets:
Cash and due from banks	$ 380,799	$ 480,998
Other assets	1,218,071	1,216,748
Total assets	25,524,604	24,902,347
Liabilities and Shareholders' Equity:
Long-term debt	505,173	505,192
Shareholders' equity	2,940,095	2,834,281	$ 2,702,894	$ 1,645,202
Total liabilities and shareholders’ equity	25,524,604	24,902,347
Parent
Assets:
Cash and due from banks	99,638	142,950
Investment securities	1,553	1,553
Investment in subsidiaries, at equity in underlying value of their net assets	3,087,651	2,936,865
Other assets	16,565	20,479
Total assets	3,205,407	3,101,847
Liabilities and Shareholders' Equity:
Long-term debt	248,443	249,935
Accrued and other liabilities	16,869	17,631
Shareholders' equity	2,940,095	2,834,281
Total liabilities and shareholders’ equity	$ 3,205,407	$ 3,101,847