Shareholders' Equity (Narrative) (Details) - USD ($)			12 Months Ended
	Jun. 01, 2015	Dec. 04, 2012	Dec. 31, 2016	Dec. 31, 2015	Dec. 06, 2012	Jun. 08, 2011
Class of Stock [Line Items]
Common stock par value (in usd per share)			$ 0.01	$ 0.01		$ 0.01
Exercise price of warrants or rights (in usd per share)			15.74
Preferred stock, par value (in usd per share)			0.01	$ 0.01
Conversion price (in usd per share)	$ 27.17
Common Stock [Member]
Class of Stock [Line Items]
Stock repurchase program, authorized amount					$ 100,000,000.0
Treasury stock acquired, average cost per share (in usd per share)			$ 32.02
Stock repurchase program, remaining authorized repurchase amount			$ 15,500,000
Series A [Member]
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percent)	8.50%
Preferred stock, par value (in usd per share)	$ 0.01
Preferred stock, liquidation preference per share (in usd per share)	$ 1,000
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Shares issued at conversion (in shares)	36.8046
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percent)		6.40%
Preferred stock, par value (in usd per share)		$ 0.01
Preferred stock, liquidation preference per share (in usd per share)		$ 25,000
Depository shares, issued		5,060,000
Depository share, par or stated value per share (in usd per share)		$ 25
Warrant [Member]
Class of Stock [Line Items]
Number of securities called by warrants or rights (in shares)						3,282,276
Exercise price of warrants or rights (in usd per share)						$ 18.28
Number of warrants repurchased (in shares)			10,317
Warrants outstanding (in shares)			53,027