Stockholders' Equity - Summary of Status of Stock Incentive Plans and Changes During Periods (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended			96 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018
Number of Options
Beginning balance (in shares)	109,616	259,969	329,871
Options granted (in shares)	0	0	0	0
Awards exercised (in shares)	0	(14,002)	(16,878)
Options forfeited (in shares)	(109,616)	(136,351)	(53,024)
Ending balance (in shares)	0	109,616	259,969	0
Number of options exercisable (in shares)	0	109,616	259,969	0
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 37.52	$ 34.68	$ 33.65
Options granted (in dollars per share)	0.00	0.00	0.00
Awards exercised (in dollars per share)	0.00	6.99	7.00
Options forfeited (in dollars per share)	37.52	35.24	37.09
Ending balance (in dollars per share)	0.00	37.52	34.68	$ 0.00
Weighted average exercise price exercisable (in dollars per share)	$ 0.00	$ 37.52	$ 34.68	$ 0.00
Weighted Average Contractual Life and Aggregate Intrinsic Value
Weighted average contractual life outstanding		5 days	6 months 10 days
Weighted average contractual life exercisable		5 days	6 months 10 days
Aggregate intrinsic value outstanding	$ 0	$ 0	$ 246	$ 0
Aggregate intrinsic value exercisable	$ 0	$ 0	$ 246	$ 0