Stock-based compensation plans (Tables)

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Restricted Stock and Restricted Stock Unit Activity

A summary of restricted stock and restricted stock unit activity follows:

	Restricted Stock Units Outstanding			Weighted- Average Grant Price		Restricted Stock Outstanding			Weighted- Average Grant Price
Unvested at January 1, 2021		816,950		$	169.60		13,550		$	162.50
Granted		636,956			132.85		—			—
Vested		(379,155	)		170.80		(9,474	)		162.57
Cancelled		(36,059	)		149.61		—			—
Unvested at December 31, 2021		1,038,692		$	147.32		4,076		$	162.35

Summary of Stock Option Activity

A summary of stock option activity follows:

				Weighted-Average
	Stock Options Outstanding			Exercise Price		Life (In Years)		Aggregate Intrinsic Value (In thousands)
Outstanding at January 1, 2021		465,423		$	174.11
Granted		178,441			132.47
Exercised		(2,699	)		113.06
Expired		(5,301	)		169.24
Outstanding at December 31, 2021		635,864		$	162.73		7.8	$	3,762
Exercisable at December 31, 2021		282,081		$	177.02		6.9	$	—