Equity Awards - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of shares
Grants (in shares)	0	0	0
Weighted- average exercise price
Grants, weighted-average exercise price (in dollars share)	$ 0	$ 0	$ 0
Stock options
Number of shares
Beginning balance (in shares)	46,096	256,246	100,000
Awards assumed through acquisition of CEC (in shares)			319,846
Exercise of stock options, net (in shares)	(20,522)	(208,114)	(162,831)
Forfeitures/expirations (in shares)	0	(2,036)	(769)
Ending balance (in shares)	25,574	46,096	256,246	100,000
Exercisable (in shares)	20,954
Weighted- average exercise price
Beginning Balance, weighted-average exercise price (in dollars share)	$ 63.49	$ 66.80	$ 51.95
Awards assumed through acquisition of CEC, weighted-average exercise price (in dollars share)			66.98
Exercises, weighted-average exercise price (in dollars share)	60.62	67.61	$ 58.11
Forfeitures/Expirations, weighted-average exercise price (in dollars share)	0	58.38	51.96
Ending Balance, weighted-average exercise price (in dollars share)	65.80	$ 63.49	$ 66.80	$ 51.95
Weighted-average exercise price (in dollars per share)	$ 60.98
Weighted-average remaining contractual life (years)	5 years	5 years 2 months 12 days	7 years	3 years 1 month 6 days
Exercisable, weighted-average remaining contractual life (years)	4 years 9 months 18 days
Aggregate intrinsic value	$ 755	$ 4,398	$ 11,947	$ 3,763
Exercisable, aggregate intrinsic value	$ 720