Stockholders' Equity (Stock Repurchase Program) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021	Nov. 02, 2020	Dec. 31, 2013
Share-based Payment Arrangement [Abstract]
Stock repurchase program, authorized amount	$ 117,700	$ 117,700	$ 250,000
Number of shares authorized to be repurchased under the Repurchase Program (in shares)				10,000,000.0
Number of remaining shares authorized to be repurchased under the Repurchase Program (in shares)				6,600,000
Shares repurchased and retired (in shares)	5,659,551	11,606,229
Average cost per share (usd per share)	$ 4.19	$ 4.14
Cost for shares repurchased	$ 23,700	$ 48,100
Payments for fees and commissions paid to the sales agent	$ 57	$ 116