Stock Based Compensation Roll Forward Schedule of Stock Option Plan by Shares and Weighted Average Exercise Prices (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Roll Forward of Shares Outstanding [Roll Forward]
Outstanding, Beginning Balance, in shares	397,177
Granted, in shares	75,518	10,404	78,848
Exercised, in shares	(62,269)
Forfeited, in shares	(8,984)
Outstanding, Ending Balance, in shares	401,442	397,177
Exercisable at December 31, 2014, in shares	266,654
Vested and Expected to Vest, in shares	134,788
Roll Forward of Shares Outstanding - Weighted Average Exercise Price: [Roll Forward]
Outstanding, Beginning Balance, in Weighted Average Exercise Price,	$ 22.44
Granted, in Weighted Average Exercise Price	$ 24.51
Exercised, in Weighted Average Exercise Price	$ 23.35
Forfeited, in Weighted Average Exercise Price	$ 23.89
Outstanding, Ending Balance, in Weighted Average Exercise Price,	$ 22.66	$ 22.44
Exercisable at December 31, 2014, in Weighted Average Exercise Price	$ 21.74
Vested and Expected to Vest, in Weighted Average Exercise Price	$ 24.47
Outstanding at December 31, 2014, Weighted Average Remaining Contractual Life, in years	5 years 9 months 28 days
Exercisable at December 31, 2014, Weighted Average Remaining Contractual Life, in years	4 years 8 months 3 days
Vested and Expected to Vest, Weighted Average Remaining Contractual Life, in years	8 years 1 month 16 days
Outstanding at December 31, 2014, Aggregate Intrinsic Value	$ 1,939
Exercisable at December 31, 2014, Aggregate Intrinsic Value	1,533
Vested and Expected to Vest, Aggregate Intrinsic Value	$ 406
Shares Available for Grant at Period End, in shares	445,000