Earnings per Share Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share Calculation [Line Items]
Net Income, Including Portion Attributable to Noncontrolling Interest	$ 15,570	$ 13,617	$ 38,488	$ 39,803
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Preferred Dividends	(1,218)	(1,218)	(3,656)	(3,656)
Net income to common shareholders	14,352	12,399	34,832	36,147
Net Income Available to Common Stockholders, Diluted	$ 15,226	$ 13,263	$ 37,456	$ 38,754
Weighted Average Number of Shares Outstanding, Basic	24,605	24,474	24,551	24,454
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Stock Options	244	214	238	223
Incremental Common Shares Attributable to Deferred Compensation	133	148	147	138
Weighted Average Number of Shares Outstanding, Diluted	30,067	29,921	30,021	29,900
Earnings Per Share, Basic	$ 0.58	$ 0.51	$ 1.42	$ 1.48
Earnings Per Share, Diluted	$ 0.51	$ 0.44	$ 1.25	$ 1.30
Anti-dilutive stock equivalent awards not included in the calculation of diluted loss per share	1,460	1,286	1,443	1,243
2017 Convertible Senior Notes [Member]
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Interest on Convertible Debt, Net of Tax	$ 372	$ 368	$ 1,117	$ 1,110
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	$ 496	$ 1,507	$ 1,497
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