Stockholders' Equity - Stock Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stockholders’ Equity
Average purchase price per share for share repurchase (in dollars per share)			$ 15.00	$ 17.82
Aggregate cost			$ 7,073	$ 72,463
Remaining authorized repurchase amount	$ 35,800		$ 35,800
Common Stock
Stockholders’ Equity
Shares repurchased during the period (in shares)	0	3,300,335	471,500	4,065,160