Shareholders' Equity (Changes in Shares by Class) (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares outstanding	129,547,032	136,122,843
Stock options exercised	338,808	178,176	65,109
Preferred Shares Issued [Member] | Series A Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	0	0	968,000
Settlement of prepaid common stock purchase contracts			0
Restricted share unit activity	0	0	0
Stock options exercised	0	0	0
Treasury stock, shares, acquired	0	0
Redemption of Series A Preferred Stock			(968,000)
Balance	0	0	0
Preferred Shares Issued [Member] | Series C Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	5,200,000	5,200,000	0
Settlement of prepaid common stock purchase contracts			0
Issuance of common stock			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	139,950,000	139,721,000	113,182,000
Common stock, shares outstanding	129,547,000	136,123,000	138,908,000	112,369,000
Settlement of prepaid common stock purchase contracts			17,550,000
Restricted share unit activity	304,000	52,000	374,000
Issuance of common stock			8,553,000
Stock options exercised	338,000	177,000	62,000
Redemption of Series A Preferred Stock	(7,218,000)	(3,014,000)
Balance	140,592,000	139,950,000	139,721,000
Treasury Shares Held [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	3,827,000	813,000	813,000
Settlement of prepaid common stock purchase contracts			0
Restricted share unit activity	0	0	0
Issuance of common stock			0
Stock options exercised	0	0	0
Treasury stock, shares, acquired	7,218,000	3,014,000
Balance	11,045,000	3,827,000	813,000