Stock-Based Plans (Summary of Stock Option Activity) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	May 14, 2020
Stock-based plans
Common stock reserved for future issuance (in shares)					1,350,000
Stock Options
Stock options outstanding at the beginning of the period (in shares)			721,496
Granted (in shares)			3,000
Exercised (in shares)			(57,058)
Forfeited (in shares)			(245,100)
Expired (in shares)			(23,688)
Stock options outstanding at the end of the period (in shares)	398,650		398,650
Weighted-average Exercise Price
Stock options outstanding at the beginning of the period (in dollars per share)			$ 104.55
Granted (in dollars per share)			75.82
Exercised (in dollars per share)			67.24
Forfeited (in dollars per share)			122.31
Expired (in dollars per share)			100.24
Stock options outstanding at the end of the period (in dollars per share)	$ 99.02		$ 99.02
Stock based compensation expense			$ 4,000,000	$ 9,902,000
Stock Options
Weighted-average Exercise Price
Stock based compensation expense	$ (1,500,000)	$ 700,000	(2,100,000)	2,200,000
Share based compensation costs capitalized		$ 0	$ 200,000	$ 400,000