Earnings per Share Earnings per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share Calculation [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 125,311		$ 8,314	$ 137,162	$ 8,332
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Preferred Dividends	(1,219)	1,219	0	(2,438)	0
Excess of fair value over book value of preferred shares redeemed	0		0	(2,190)	0
Net Income (Loss) Available to Common Stockholders, Diluted	125,527		8,442	136,218	8,332
Weighted Average Number of Shares Outstanding, Basic	24,358		19,434	23,642	19,014
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Stock Options	183		187	246	92
Incremental Common Shares Attributable to Deferred Compensation	119		127	111	132
Weighted Average Number of Shares Outstanding, Diluted	29,745		20,273	28,410	19,238
Earnings Per Share, Basic	$ 5.09		$ 0.43	$ 5.61	$ 0.44
Earnings Per Share, Diluted	$ 4.22		$ 0.42	$ 4.79	$ 0.43
Anti-dilutive stock equivalent awards not included in the calculation of diluted loss per share	998		695	951	1,003
2017 Convertible Senior Notes [Member]
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Interest on Convertible Debt, Net of Tax	611		128	1,833	0
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Conversion of Debt Securities	2,416		525	2,416	0
2018 Convertible Senior Notes [Member]
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Interest on Convertible Debt, Net of Tax	$ 824		$ 0	$ 1,851	$ 0
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Conversion of Debt Securities	2,669		0	1,995	0