Equity Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Equity Compensation
Unrecognized compensation expense	$ 2,300		$ 2,300
Compensation Expense	2,076	$ 742	5,614		$ 3,081
Tax Benefit Recognized	$ 777	$ 271	$ 2,082		$ 1,127
Time-Vested Restricted Stock Awards
Assumptions used for estimating fair value of grants outstanding
Vesting period	3 years
Changes in restricted stock awards
Nonvested, balance at the beginning of the period (in shares)	55,600	41,000	55,600	41,000
Granted (in shares)	18,400	19,000
Distributed (in shares)	(18,500)	(1,654)
Forfeited shares (in shares)		(2,746)
Nonvested, balance at the end of the period (in shares)	55,500	55,600	55,500	55,600	55,600
Weighted Average Grant Date Fair Value
Nonvested, balance at the beginning of the period (in dollars per share)	$ 24.60	$ 21.89	$ 24.60	$ 21.89
Granted (in dollars per share)	29.53	30.40
Distributed (in dollars per share)	21.36	21.92
Forfeited shares ( in dollars per share)				25.91
Nonvested, balance at the end of the period (in dollars per share)	$ 27.31	$ 24.60	$ 27.31	$ 24.60	$ 24.60
Performance-Based Restricted Stock Awards
Changes in restricted stock awards
Nonvested, balance at the beginning of the period (in shares)	69,021	63,300	69,021	63,300
Target shares granted (in shares)	22,400	21,800
Shares issued in excess of target (in shares)	18,403	3,653
Shares awarded (in shares)	(43,036)	(13,653)
Forfeited shares (in shares)		(6,079)
Nonvested, balance at the end of the period (in shares)	66,788	69,021	66,788	69,021	69,021
Weighted Average Grant Date Fair Value
Nonvested, balance at the beginning of the period (in dollars per share)	$ 24.38	$ 21.74	$ 24.38	$ 21.74
Target shares granted (in dollars per share)	$ 29.53	$ 30.40
Shares issued in excess of target (in dollars per share)	21.36	30.55
Shares awarded (in dollars per share)	$ 21.36	$ 30.55
Forfeited shares ( in dollars per share)		24.10
Nonvested, balance at the end of the period (in dollars per share)	$ 27.22	$ 24.38	$ 27.22	$ 24.38	$ 24.38