Businss Combinations (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
	Sep. 02, 2016	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 01, 2016	May 06, 2016	Mar. 11, 2016	Feb. 13, 2015
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value			$ 80,690	$ 154,496
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value						$ 241,392
FDIC Indemnification Asset, Acquisitions			0	0	$ 5,106
Gain on acquisitions			5,831	42,930	0
Merger-related expenses			5,341	14,174	13,064
Goodwill			150,601	139,773	$ 139,773
Cordia Bancorp Inc.
Business Acquisition [Line Items]
Business Acquisition, Share Price						$ 5.15
Total purchase price	$ 37,053
Cash and due from banks						$ 8,383
Overnight investments						3,081
Investment securities						76,633
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value						241,392
Premises and equipment						4,151
Other real estate owned						1,170
Income earned not collected						1,990
Other intangible assets						2,210
Other assets						10,318
Total assets acquired						349,328
Deposits						292,192
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Federal Funds Purchased						30,164
Other liabilities						747
Total liabilities assumed						323,103
Fair value of net assets (liabilities) acquired						26,225
Goodwill acquired			10,828	0
Revenue of acquired business			4,226
Merger-related expenses			3,810
Goodwill						$ 10,828
Capitol City Bank and Trust
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value									$ 154,496
Other intangible assets									690
Total assets acquired									211,935
Deposits									266,352
Gain on acquisitions				42,930
Bargain Purchase After Tax Gain				26,400
Total liabilities assumed									272,520
Fair value of net assets (liabilities) acquired									(60,585)
Business Combination Cash Received From FDIC In Acquisition									$ 103,515
Revenue of acquired business				8,300
Merger-related expenses				$ 1,900
First CornerStone Bank
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value							$ 43,776
Cash and due from banks							748
Overnight investments							37,540
Investment securities							4,564
Other real estate owned							375
Income earned not collected							8
Other intangible assets							390
Other assets							13
Total assets acquired							87,414
Deposits							96,882
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period		$ 837	837
Gain on acquisitions			2,959
Other liabilities							23
Total liabilities assumed							96,905
Fair value of net assets (liabilities) acquired							(9,491)
Business Combination Cash Received From FDIC In Acquisition							$ 12,450
Revenue of acquired business			1,600
Merger-related expenses			1,000
North Milwaukee State Bank
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value								$ 36,914
Cash and due from banks								4,545
Overnight investments								2,274
Investment securities								9,425
Other intangible assets								240
Other assets								216
Total assets acquired								53,614
Deposits								59,206
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Federal Funds Purchased								1,662
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period			1,200
Gain on acquisitions			2,872
Other liabilities								74
Total liabilities assumed								60,942
Fair value of net assets (liabilities) acquired								7,328
Business Combination Cash Received From FDIC In Acquisition								$ 10,200
Revenue of acquired business			1,900
Merger-related expenses			$ 500