Employee Benefits - Equity Incentive Plans (Details) $ in Thousands				3 Months Ended		9 Months Ended
	Jun. 30, 2010 shares	May 18, 2007 shares	Jun. 21, 2006 shares	Sep. 30, 2017 USD ($) item shares	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) item shares	Sep. 30, 2016 USD ($)	Dec. 31, 2016 shares	Jul. 28, 2014 shares
Employee Benefits
Number of stock option plans frozen | item				2		2
Share-based Compensation | $						$ 1,700	$ 951
Percentage of participant's contribution matched by Company						100.00%
Company contributions | $				$ 349	$ 325	$ 1,100	976
Restricted Stock Units (RSUs)
Employee Benefits
Units outstanding				322,375		322,375
Total stock-based compensation expense | $				$ 186	193	$ 592	595
Employee And Directors Time Based Options
Employee Benefits
Options outstanding								377,015
Employee And Directors Performance Options
Employee Benefits
Options outstanding								1,020,242
Stock Appreciation Rights (SARs)
Employee Benefits
Total stock-based compensation expense | $						$ 642
Allocated share based compensation expense reversal | $					$ 114		$ 2
2014 Plan
Employee Benefits
Options outstanding				429,500		429,500		389,500
2014 Plan | Restricted Stock Units (RSUs)
Employee Benefits
Number of units granted						275,000
Units outstanding								288,500
2010 Option Plan | Employee And Directors Stock Options
Employee Benefits
Number of shares or units authorized for grants	2,239,906
Vesting period	4 years
2010 Option Plan | Employee And Directors Time Based Options
Employee Benefits
Options outstanding				367,213		367,213
2010 Option Plan | Employee And Directors Performance Options
Employee Benefits
Options outstanding				992,864		992,864
2010 Option Plan | Employee And Directors Super Performance Options
Employee Benefits
Options outstanding				308,054		308,054		316,550
2006 Option Plan
Employee Benefits
Number of shares or units authorized for grants			450,000
Options outstanding				87,500		87,500		127,500
Vesting period			4 years
Term of awards			10 years
SAR Plan
Employee Benefits
Number of shares or units authorized for grants		200,000
Units outstanding				63,000		63,000		93,000
Term of awards		10 years
Allocated share based compensation expense reversal | $				$ 285
2014 Option Plan
Employee Benefits
Number of shares or units authorized for grants									1,273,838
Maximum
Employee Benefits
Percentage of participant's salary matched by Company						6.00%