Mergers and Acquisitions - Purchase Price Adjustment (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		6 Months Ended
		Sep. 01, 2013	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Business Acquisition [Line Items]
Deal charges			$ 1,467	$ 0	$ 1,945	$ 195
Goodwill resulting from merger			$ 274,698	$ 276,146	$ 274,698	$ 276,146	$ 274,706
First M&F Merger
Business Acquisition [Line Items]
Shares issued to common shareholders		6,175,576
Purchase price per share (usd per share)		$ 25.17
Value of stock paid		$ 155,439
Cash paid for fractional shares		17
Fair value of stock based compensation assumed		68
Deal charges		1,321
Total Purchase Price		156,845
Stockholders’ equity at 9/1/13		79,440
Total Net Assets Acquired		66,718
Goodwill resulting from merger	[1]	90,127
Deposits | First M&F Merger
Business Acquisition [Line Items]
Fair value adjustment of liabilities		(3,207)
Junior Subordinated Debt | First M&F Merger
Business Acquisition [Line Items]
Fair value adjustment of liabilities		12,371
Other liabilities | First M&F Merger
Business Acquisition [Line Items]
Fair value adjustment of liabilities		1,748
Deferred income taxes | First M&F Merger
Business Acquisition [Line Items]
Fair value adjustment of liabilities		10,210
Securities | First M&F Merger
Business Acquisition [Line Items]
Fair value adjustment of assets		253
Loans, net of First M&F's allowance for loan losses | First M&F Merger
Business Acquisition [Line Items]
Fair value adjustment of assets	[2]	(45,761)
Fixed assets | First M&F Merger
Business Acquisition [Line Items]
Fair value adjustment of assets		(3,254)
Core deposits intangible, net of First M&F’s existing core deposit intangible | First M&F Merger
Business Acquisition [Line Items]
Fair value adjustment of assets		21,158
Other real estate owned | First M&F Merger
Business Acquisition [Line Items]
Fair value adjustment of assets	[2]	(5,797)
Other assets | First M&F Merger
Business Acquisition [Line Items]
Fair value adjustment of assets		$ (443)

[1] The goodwill resulting from the merger has been assigned to the Community Banks operating segment.

[2] The fair value adjustments to acquired loans and other real estate owned reflect management’s expectations to more aggressively market and liquidate problem assets quickly.