Share-based Compensation - Stock Options and Restricted Stock Activity (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Stock options
Options Outstanding
Balance at beginning of period (in shares)	784,995	1,007,665
Granted (in shares)	0	0
Exercised (in shares)	0	0
Lapsed or cancelled (in shares)	(68,015)	(222,670)
Balance at end of period (in shares)	716,980	784,995
Options exercisable at end of period (in shares)	716,980	782,022
Weighted Average Exercise Price
Balance at beginning of year (in dollars per share)	$ 102.62	$ 105.35
Granted (in dollars per share)	0	0
Exercised (in dollars per share)	0	0
Lapsed or cancelled (in dollars per share)	100.95	114.97
Balance at end of period (in dollars per share)	102.77	102.62
Options exercisable at end of period (in dollars per share)	$ 102.77	$ 102.62
Restricted Stock Awards
Options Outstanding
Total fair value of options granted during the period	$ 9,214,531	$ 734,315
Summary of restricted stock
Balance at beginning of year (in shares)	3,439,674	3,465,347
Granted (in shares)	145,845	8,959
Cancelled (in shares)	(19,236)	(34,632)
Balance at end of period (in shares)	3,566,283	3,439,674
Vested during the period (in shares)	126,515	128,891