Parent Company Financial Information (Condensed Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assets
Cash and due from banks	$ 171,221	$ 165,030
Interest-earning deposits	16,949	14,531
Total cash and cash equivalents	188,170	179,561	513,926	294,289
Other assets	231,877	217,289
Total Assets	8,578,846	7,161,582
Liabilities and Shareholders’ Equity
Other borrowings	8,248	0
Other liabilities	96,053	87,252
Total liabilities	7,350,671	6,108,333
Shareholders’ equity	1,228,175	1,053,249	764,008	759,338
Total liabilities and shareholders' equity	8,578,846	7,161,582
Parent Company [Member]
Assets
Cash and due from banks	10,322	3,006
Interest-earning deposits	12,274	50,678
Total cash and cash equivalents	22,596	53,684	86,644	75,234
Other assets	5,273	1,952
Total Assets	1,240,363	1,053,675
Liabilities and Shareholders’ Equity
Other borrowings	8,248	0
Other liabilities	3,940	426
Total liabilities	12,188	426
Shareholders’ equity	1,228,175	1,053,249
Total liabilities and shareholders' equity	1,240,363	1,053,675
Banking Subsidiaries [Member] | Parent Company [Member]
Assets
Investment in subsidiaries	1,207,143	993,002
Other Subsidiaries [Member] | Parent Company [Member]
Assets
Investment in subsidiaries	$ 5,351	$ 5,037