Earnings per Share Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share Calculation [Line Items]
Net Income, Including Portion Attributable to Noncontrolling Interest	$ 15,916	$ 13,350	$ 25,105	$ 22,918
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Preferred Dividends	(1,219)	(1,219)	(2,438)	(2,438)
Net income to common shareholders	14,697	12,131	22,667	20,480
Net Income Available to Common Stockholders, Diluted	$ 15,613	$ 13,006	$ 24,484	$ 22,230
Weighted Average Number of Shares Outstanding, Basic	24,669	24,531	24,663	24,523
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Stock Options	185	243	177	233
Incremental Common Shares Attributable to Deferred Compensation	138	164	130	161
Weighted Average Number of Shares Outstanding, Diluted	30,077	30,023	30,055	30,002
Earnings Per Share, Basic	$ 0.60	$ 0.49	$ 0.92	$ 0.84
Earnings Per Share, Diluted	$ 0.52	$ 0.43	$ 0.81	$ 0.74
Anti-dilutive stock equivalent awards not included in the calculation of diluted loss per share	1,261	1,486	1,301	1,428
2017 Convertible Senior Notes [Member]
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Interest on Convertible Debt, Net of Tax	$ 390	$ 373	$ 774	$ 745
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	$ 526	$ 502	$ 1,043	$ 1,005
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