Equity-Based Compensation - (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee stock-based compensation expense
Equity-based compensation expense	$ 2,900	$ 2,330	$ 1,453
Restricted Stock Units
Vesting Period	3 years
Proceeds from exercise of stock options		101	2,248
Aggregate Intrinsic Value, Options Outstanding	$ 0	900	19,200
Options, Exercised	0
Options exercised	0
2013 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized	3,576,466
Employee stock-based compensation expense
Equity-based compensation expense	$ 2,900	2,330	1,453
Tax benefit from share-based compensation	(637)	(511)	(231)
Excess tax benefit from share-based compensation	(324)	(261)	(2,770)
Net compensation cost	$ 1,939	$ 1,558	$ (1,548)
Time-based Restricted Stock Units
Restricted Stock Units
Nonvested at beginning of period	127,011
Granted	43,450
Shares vested (including tax withholding)	(58,426)
Forfeited	(6,173)
Nonvested at end of period	105,862	127,011
Nonvested at beginning of period, Weighted average grant date fair value per share	$ 33.00
Granted, Weighted average grant date fair value per share	55.45	$ 33.24	$ 32.45
Shares vested (including tax withholding), Weighted average grant date fair value per share	33.03
Forfeited, Weighted average grant date fair value per share	41.94
Nonvested at end of period, Weighted average grant date fair value per share	$ 41.67	$ 33.00
Unrecognized compensation cost	$ 2,200
Period for recognition of RSU compensation expense	1 year 6 months 7 days
Time-based Restricted Stock Units | 2013 Stock Incentive Plan
Employee stock-based compensation expense
Equity-based compensation expense	$ 2,523	$ 2,330	$ 1,453
Time-based Restricted Stock Units | Directors
Restricted Stock Units
Vesting Period	1 year
Time-based Restricted Stock Units | Employees
Restricted Stock Units
Vesting Period	3 years
Performance-based Restricted Stock Units
Restricted Stock Units
Granted	33,961
Forfeited	(2,130)
Nonvested at end of period	31,831
Granted, Weighted average grant date fair value per share	$ 57.88
Forfeited, Weighted average grant date fair value per share	57.88
Nonvested at end of period, Weighted average grant date fair value per share	$ 57.88
Period of performance measurement	3 years
Unrecognized compensation cost	$ 900
Period for recognition of RSU compensation expense	2 years
Performance-based Restricted Stock Units | Minimum
Restricted Stock Units
Shares issued upon participants target award	0.00%
Performance-based Restricted Stock Units | Maximum
Restricted Stock Units
Shares issued upon participants target award	150.00%
Performance-based Restricted Stock Units | 2013 Stock Incentive Plan
Employee stock-based compensation expense
Equity-based compensation expense	$ 377
Restricted Stock Units (RSUs)
Restricted Stock Units
Additional shares available to grant under plan (in shares)	2,400,857