Stock Incentive Plans - 2016 Equity Compensation Plan Stock Options Activity (Details) - Employee Stock Option - 2016 Equity Compensation Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Options
Balance outstanding beginning of period, options (in shares)	26,000	93,119
Options vested but not exercised (in shares)	(13,000)	(66,476)
Forfeited, options (in shares)		(643)
Balance outstanding end of period, options (in shares)	13,000	26,000
Weighted Average Exercise Price
Beginning balance, Weighted-average exercise price (in dollars per share)	$ 38.92	$ 33.04
Vested and unexercised (in dollars per share)	38.92	38.92
Ending balance, Weighted-average exercise price (in dollars per share)	38.92	38.92
Fair Value of Options on grant date
Beginning balance, Fair Value of Options on Grant Date (in dollars per share)	18.20
Vested and unexercised, fair value (in dollars per share)	(9.10)	19.10
Forfeitures, fair value of options on grant date (in dollars per share)	$ 9.10	18.20
Ending balance, Fair Value of Options on Grant Date (in dollars per share)		$ 18.20
Aggregate fair value (in millions)
Balance outstanding beginning of period, aggregate fair value	$ 470	$ 1,750
Vested and unexercised, aggregate fair value	(240)	(1,270)
Forfeited, aggregate fair value	$ 230	(10)
Balance outstanding end of period, aggregate fair value		$ 470
Forfeitures exercise price (in dollars per share)		$ 38.92