Earnings per Share Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share Calculation [Line Items]
Net Income, Including Portion Attributable to Noncontrolling Interest	$ 27,911	$ 16,989	$ 45,974	$ 33,872
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Preferred Dividends	0	(1,219)	0	(2,438)
Net income to common shareholders	27,911	15,770	45,974	31,434
Net Income Available to Common Stockholders, Diluted	$ 27,911	$ 16,688	$ 46,383	$ 33,271
Weighted Average Number of Shares Outstanding, Basic	28,571	24,990	28,349	24,864
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Stock Options	353	335	409	330
Incremental Common Shares Attributable to Deferred Compensation	177	209	194	192
Diluted Weighted Average Number of Shares Outstanding, Adjusted for Assumed Conversions	29,101	30,619	29,818	30,471
Earnings Per Share, Basic	$ 0.98	$ 0.63	$ 1.62	$ 1.26
Earnings Per Share, Diluted	$ 0.96	$ 0.55	$ 1.56	$ 1.09
Anti-dilutive stock equivalent awards not included in the calculation of diluted loss per share	434	0	326	47
2017 Convertible Senior Notes [Member]
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Interest on Convertible Debt, Net of Tax	$ 0	$ 391	$ 0	$ 782
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Conversion of Debt Securities	0	2,416	0	2,416
2018 Convertible Senior Notes [Member]
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Interest on Convertible Debt, Net of Tax	$ 0	$ 527	$ 409	$ 1,055
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Conversion of Debt Securities	0	2,669	866	2,669