Equity (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 26, 2013
Class of Stock [Line Items]
Common shares par value (in usd per share)	$ 0.001	$ 0.001
Common shares authorized (shares)	250,000,000
Amount authorized for repurchase under share repurchase authorization				$ 350,000,000
Purchase of common stock (in shares)	0	6,500,000	10,600,000
Purchase of common stock	$ 0	$ 85,926,000	$ 145,858,000
Amount remaining for repurchase under share repurchase authorization	$ 118,700,000
Preferred stock authorized (shares)	4,000,000	4,000,000
Preferred stock issued (shares)	0	0
Preferred stock outstanding (shares)	0	0
Preferred shares par value (in usd per share)	$ 0.001	$ 0.001
Dividend rate (percent)	6.00%
Penalty dividend rate (percent)	8.00%
Accrued dividends	$ 3,000,000	$ 3,000,000	$ 3,067,000
Conversion price per share at option of holder (in dollars per share)	$ 14.50
Conversion price per share at option of company (in dollars per share)	$ 29.00
Number of consecutive trading days	20 days
Anti-dilutive Series A preferred shares not included in the calculation of EPS (shares)	13,793,100
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock authorized (shares)	1,000,000.0
Preferred stock issued (shares)	200,000
Preferred shares par value (in usd per share)	$ 0.001
Stated value of preferred shares per share (in dollars per share)	$ 1,000
Percent of stated value (percent)	100.00%
Preferred stock redemption value	$ 200,000,000
Maximum percent of stated value (percent)	101.00%