Shareholders' Equity (Changes in Shares by Class) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares outstanding	122,266,106	129,547,032
Issuance of common stock for acquisition	$ 26,592
Stock options exercised	297,225	338,808	178,176
Preferred Shares Issued [Member] | Series C Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	5,200,000	5,200,000	5,200,000
Balance	5,200,000	5,200,000	5,200,000
Common Shares Issued [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	140,592,000	139,950,000	139,721,000
Common stock, shares outstanding	122,266,000	129,547,000	136,123,000	138,908,000
Issuance of common stock for acquisition	$ 821
Restricted share unit activity	316,000	304,000	52,000
Stock options exercised	297,000	338,000	177,000
Repurchase of common stock	(8,715,000)	(7,218,000)	(3,014,000)
Balance	142,026,000	140,592,000	139,950,000
Treasury Shares Held [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	11,045,000	3,827,000	813,000
Restricted share unit activity	0	0	0
Stock options exercised	0	0	0
Repurchase of common stock	8,715,000	7,218,000	3,014,000
Balance	19,760,000	11,045,000	3,827,000