Stockholders' Equity - Changes in Shares of Common Stock Outstanding (Details) - Common Stock - shares shares in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Common stock shares outstanding:
Shares outstanding at beginning of year (in shares)	3,636	3,636	3,636
Shares exercised under stock option plan (in shares)	0	0	0
Shares outstanding at end of year (in shares)	3,636	3,636	3,636