Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended						3 Months Ended								12 Months Ended
	Dec. 31, 2016	Dec. 19, 2008	Jan. 31, 2017	Jun. 30, 2016	Jul. 31, 2015	Jun. 30, 2015	Jan. 31, 2015	Mar. 31, 2012	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jun. 25, 2015
Shareholders' Equity [Line Items]
Common stock, shares authorized	100,000,000			3,000,000					100,000,000		3,000,000		100,000,000				100,000,000	100,000,000
Proceeds from the issuance of common stock, net				$ 152,900													$ 152,911	$ 0	$ 0
Cash dividends declared per common share (usd dollars per share)									$ 0.12	$ 0.12	$ 0.12	$ 0.12	$ 0.11	$ 0.11	$ 0.11	$ 0.11	$ 0.48	$ 0.44	$ 0.40
Series C preferred stock
Shareholders' Equity [Line Items]
Preferred stock, shares issued	126,257							126,500	126,257				126,287				126,257	126,287
Preferred stock, value, issued	$ 126,257							$ 126,500	$ 126,257				$ 126,287				$ 126,257	$ 126,287
Preferred stock, dividend payment terms								quarterly
Preferred stock, dividend rate, percentage								5.00%
Convertible preferred stock, terms of conversion	24.5569								24.5569								24.5569
Preferred stock, shares converted																	30	180
Common stock, shares, conversion of preferred stock																	729	4,374
Series D preferred stock
Shareholders' Equity [Line Items]
Preferred stock, shares issued	5,000,000								5,000,000				5,000,000				5,000,000	5,000,000		5,000,000
Preferred stock, value, issued	$ 125,000								$ 125,000				$ 125,000				$ 125,000	$ 125,000		$ 125,000
Preferred stock, dividend payment terms						quarterly
Preferred stock, dividend rate, percentage						6.50%
Community Financial Shares Inc.
Shareholders' Equity [Line Items]
Shares issued in acquisitions					388,573
Delavan Bancshares
Shareholders' Equity [Line Items]
Shares issued in acquisitions							422,122
US Treasury
Shareholders' Equity [Line Items]
Warrants outstanding (in shares)	341,852	1,643,295							341,852								341,852
Exercise price of common stock (in usd per share)	$ 22.71
Warrant termination period		10 years
Warrants exercised (in shares)																	25,580
Common stock, shares, issued from exercise of warrant shares																	15,191
Subsequent Event
Shareholders' Equity [Line Items]
Cash dividends declared per common share (usd dollars per share)			$ 0.14
Common stock dividends per share declared annualized (in usd per share)			$ 0.56
Dividends payable, date to be paid			Feb. 23, 2017
Dividends payable, date of record			Feb. 09, 2017
London Interbank Offered Rate (LIBOR) | Series D preferred stock
Shareholders' Equity [Line Items]
Preferred stock, dividend rate, percentage, variable spread						4.06%