Parent Company Financial Information (Condensed Balance Sheets) (Details) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Cash and due from banks		$ 244,615	$ 193,038
Interest-earning deposits		97,918	31,200
Total cash and cash equivalents		342,533	224,238	$ 175,302	$ 188,170
Goodwill		765,842	382,762	382,762	382,537
Other assets		284,621	256,984
Total Assets		12,716,886	9,509,607
Subordinated Debt		35,647	0
Junior Subordinated Notes		8,248	0
Liabilities and Shareholders’ Equity
Other liabilities		100,346	111,865
Total liabilities		10,766,964	8,258,595
Shareholders’ equity		1,949,922	1,251,012	1,242,128	1,228,175
Total liabilities and shareholders' equity		12,716,886	9,509,607
Parent Company [Member]
Assets
Cash and due from banks		533	1,718
Interest-earning deposits		8,765	729
Total cash and cash equivalents		9,298	2,447	$ 3,989	$ 22,596
Goodwill	[1]	4,729	7
Other assets		3,426	5,139
Total Assets		1,994,398	1,251,283
Subordinated Debt		35,647	0
Junior Subordinated Notes		8,248	0
Liabilities and Shareholders’ Equity
Other liabilities		581	271
Total liabilities		44,476	271
Shareholders’ equity		1,949,922	1,251,012
Total liabilities and shareholders' equity		1,994,398	1,251,283
Banking Subsidiaries [Member] | Parent Company [Member]
Assets
Investment in subsidiaries		1,971,788	1,238,712
Other Subsidiaries [Member] | Parent Company [Member]
Assets
Investment in subsidiaries		$ 5,157	$ 4,978

[1] Reclassified to conform to current period’s presentation. The reclassification was limited to adding a separate line for Goodwill, which was previously included in other assets.