Equity-Based Compensation - Summary of Stock Option Activity Under the 2010 Plan and Equity Plan (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
2010 Equity Award Plan [Member]
Stock Option Activity, Options
Beginning of period, outstanding (in shares)	887,055	1,000,855	820,471
Options granted (in shares)	13,100	48,500	180,384
Options exercised (in shares)	(100,000)	0	0
Options canceled or forfeited (in shares)		(17,350)
Options expired (in shares)		(144,950)
End of period, outstanding (in shares)	800,155	887,055	1,000,855
Options exercisable (in shares)	639,130
Weighted-Average Exercise Price
Beginning of period (weighted-average price)	$ 11.74	$ 11.72	$ 13.21
Options granted (weighted-average price)	6.45	5.38	4.95
Options exercised (weighted-average price)	7.52
Options canceled or forfeited (weighted-average price)		9.73
Options expired (weighted-average price)		9.73
End of period (weighted-average price)	12.18	$ 11.74	$ 11.72
Options exercisable (weighted-average price)	$ 13.85
2000 Equity Award Plan [Member]
Stock Option Activity, Options
Beginning of period, outstanding (in shares)	734,425	1,170,925	1,356,375
Options exercised (in shares)	(286,875)	(232,750)	(182,500)
Options expired (in shares)		(203,750)	(2,950)
End of period, outstanding (in shares)	447,550	734,425	1,170,925
Options exercisable (in shares)	447,550
Weighted-Average Exercise Price
Beginning of period (weighted-average price)	$ 5.13	$ 4.98	$ 4.89
Options exercised (weighted-average price)	4.67	4.09	4.27
Options expired (weighted-average price)		5.48	5.79
End of period (weighted-average price)	5.42	$ 5.13	$ 4.98
Options exercisable (weighted-average price)	$ 5.42