Earnings per Share Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share Calculation [Line Items]
Net Income, Including Portion Attributable to Noncontrolling Interest	$ 22,327	$ 10,942	$ 56,199	$ 36,047
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Preferred Dividends	(1,218)	(1,218)	(3,656)	(3,656)
Excess of fair value over book value of preferred shares redeemed	(2,257)	0	(2,257)	0
Net income to common shareholders	18,852	9,724	50,286	32,391
Net Income Available to Common Stockholders, Diluted	$ 19,706	$ 10,612	$ 52,978	$ 35,097
Weighted Average Number of Shares Outstanding, Basic	25,581	24,669	25,106	24,665
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Stock Options	248	231	302	200
Incremental Common Shares Attributable to Deferred Compensation	237	154	207	143
Weighted Average Number of Shares Outstanding, Diluted	30,675	30,139	30,539	30,093
Earnings Per Share, Basic	$ 0.74	$ 0.39	$ 2.00	$ 1.31
Earnings Per Share, Diluted	$ 0.64	$ 0.35	$ 1.73	$ 1.17
Anti-dilutive stock equivalent awards not included in the calculation of diluted loss per share	0	896	31	1,288
2017 Convertible Senior Notes [Member]
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Interest on Convertible Debt, Net of Tax	$ 324	$ 378	$ 1,106	$ 1,152
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Conversion of Debt Securities	1,940	2,416	2,255	2,416
2018 Convertible Senior Notes [Member]
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Interest on Convertible Debt, Net of Tax	$ 530	$ 510	$ 1,586	$ 1,554
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Conversion of Debt Securities	2,669	2,669	2,669	2,669