Stockholders' Equity - Stock Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stockholders' Equity
Average purchase price per share for share repurchase (in dollars per share)			$ 16.54	$ 16.59
Aggregate cost			$ 8,803	$ 20,845	$ 93,369
Remaining authorized repurchase amount	$ 77,400		$ 77,400
Common Stock
Stockholders' Equity
Shares repurchased during the period (in shares)			532,034	1,263,159	5,238,566
Treasury stock, shares, retired (in shares)	532,034	1,263,159
Retirement of treasury stock	$ 8,800	$ 20,800	$ 8,803	$ 20,845	$ 93,369