Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Company's Option Activity

A summary of the Company’s option activity and related information for the three years ended December 31, 2020 is as follows:

	Number of options			Weighted- average price		Weighted- average remaining contractual term (in years)		Aggregate intrinsic value (in millions)
Balance at December 31, 2017		1,208,860		$	28.14
Options granted		—			—
Options exercised		(332,810	)		29.49
Options cancelled/forfeited/expired		(30,450	)		28.27
Balance at December 31, 2018		845,600			28.14
Options granted		—			—
Options exercised		(260,860	)		29.55
Options cancelled/forfeited/expired		(4,600	)		30.59
Balance at December 31, 2019		580,140			29.57
Options granted		—			—
Options exercised		(163,670	)		30.22
Options cancelled/forfeited/expired		(7,060	)		28.95
Balance at December 31, 2020		409,410		$	29.33		2.52	$	15.5
Exercisable at December 31, 2020		309,695		$	28.45		2.40	$	12.0
Expected to vest after December 31, 2020		97,645		$	32.05		2.95	$	3.4

Options Outstanding and Options Exercisable by Exercise Price with Weighted-Average Remaining Contractual Life for Options Outstanding and Weighted-Average Exercise Price

The following table indicates the options outstanding and options exercisable by exercise price with the weighted-average remaining contractual life for the options outstanding and the weighted-average exercise price at December 31, 2020:

	Options Outstanding						Options Exercisable
Exercise price	Number outstanding at December 31, 2020		Weighted-average remaining contractual life (Years)		Weighted-average grant date value		Number exercisable at December 31, 2020		Weighted-average grant date value
$20 – 25		206,125		2.17	$	24.60		181,480	$	24.60
$25 – 30		2,840		2.15	$	25.12		2,290	$	25.13
$30 – 35		190,585		2.88	$	33.97		119,805	$	33.79
$35 – 40		6,800		3.00	$	39.19		5,440	$	39.19
$40 – 45		3,060		3.67	$	40.37		680	$	40.37
$20 – 45		409,410		2.52	$	29.33		309,695	$	28.45

Schedule of Weighted-Average Assumptions Used to Determine Fair Value of Option Granted

Summary of Company's Restricted Stock Units Activity

The following table summarizes the activity of the Company’s RSUs, which includes service-based and performance-based awards, for the three years ended December 31, 2020:

				Weighted-		Aggregate
				average		intrinsic
	Number			grant date		value
	of shares			fair value		(in millions)
Balance at December 31, 2017		93,664		$	33.62
RSUs granted		97,260			49.47
RSUs vested		(30,214	)		33.16
RSUs cancelled/forfeited/expired		(21,200	)		33.88
Balance at December 31, 2018		139,510			44.73
RSUs granted		83,440			59.98
RSUs vested		(25,862	)		48.31
RSUs cancelled/forfeited/expired		(840	)		59.84
Balance at December 31, 2019		196,248			50.68
RSUs granted		126,540			50.99
RSUs vested		(89,225	)		43.42
RSUs cancelled/forfeited/expired		(7,593	)		57.93
Balance at December 31, 2020		225,970		$	57.06	$	15.2