Earnings per Share Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share Calculation [Line Items]
Net Income, Including Portion Attributable to Noncontrolling Interest	$ 13,350	$ 13,554	$ 22,918	$ 26,186
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Preferred Dividends	(1,219)	(1,219)	(2,438)	(2,438)
Net income to common shareholders	12,131	12,335	20,480	23,748
Net Income Available to Common Stockholders, Diluted	$ 13,006	$ 13,235	$ 22,230	$ 25,494
Weighted Average Number of Shares Outstanding, Basic	24,531	24,470	24,523	24,444
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Stock Options	243	218	233	228
Incremental Common Shares Attributable to Deferred Compensation	164	140	161	134
Weighted Average Number of Shares Outstanding, Diluted	30,023	29,913	30,002	29,891
Earnings Per Share, Basic	$ 0.49	$ 0.50	$ 0.84	$ 0.97
Earnings Per Share, Diluted	$ 0.43	$ 0.44	$ 0.74	$ 0.85
Anti-dilutive stock equivalent awards not included in the calculation of diluted loss per share	1,486	1,287	1,428	1,221
2017 Convertible Senior Notes [Member]
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Interest on Convertible Debt, Net of Tax	$ 373	$ 383	$ 745	$ 744
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Conversion of Debt Securities	2,416	2,416	2,416	2,416
2018 Convertible Senior Notes [Member]
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Interest on Convertible Debt, Net of Tax	$ 502	$ 517	$ 1,005	$ 1,002
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