Employee Benefit Plans - Status of Restricted Stock Awarded under Restricted Stock Plan (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non vested balance at beginning of period (in shares)	0	128,500	278,900
Granted (in shares)		0	13,585
Forfeited (in shares)		0	(30,800)
Vested (in shares)		(128,500)	(133,185)
Non vested balance at end of period (in shares)	0	0	128,500
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Non vested balance at beginning of period (in dollars per share)	$ 0.00	$ 5.85	$ 6.28
Granted (in dollars per share)		0.00	17.02
Forfeited (in dollars per share)		0.00	6.27
Vested (in dollars per share)		5.85	7.80
Non vested balance at end of period (in dollars per share)		$ 0.00	$ 5.85
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non vested balance at beginning of period (in shares)	527,486	437,946	413,288
Granted (in shares)	47,514	100,892	89,702
Forfeited (in shares)	(3,508)	(11,352)	(54,506)
Vested (in shares)	(203,000)	0	(10,538)
Non vested balance at end of period (in shares)	368,492	527,486	437,946
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Non vested balance at beginning of period (in dollars per share)	$ 10.17	$ 7.09	$ 5.09
Granted (in dollars per share)	42.93	23.15	16.63
Forfeited (in dollars per share)	25.74	11.55	6.15
Vested (in dollars per share)	4.82	0.00	14.88
Non vested balance at end of period (in dollars per share)	$ 17.20	$ 10.17	$ 7.09