Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2019

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, 2019 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, 2016		1,584,435		$	28.14
Options granted		299,600			34.66
Options exercised		(398,275	)		28.94
Options cancelled/forfeited/expired		(276,900	)		28.04
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		3.31	$	27.2
Exercisable at December 31, 2019		289,350		$	29.35		3.00	$	13.6
Expected to vest after December 31, 2019		289,003		$	29.80		3.61	$	13.5

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, 2019:

	Options Outstanding						Options Exercisable
Exercise price	Number outstanding at December 31, 2019		Weighted-average remaining contractual life (Years)		Weighted-average grant date value		Number exercisable at December 31, 2019		Weighted-average grant date value
$20 – 25		256,640		3.17	$	24.60		128,440	$	24.60
$25 – 30		6,150		3.13	$	25.13		1,120	$	25.14
$30 – 35		306,810		3.40	$	33.48		155,710	$	33.04
$35 – 40		6,800		4.00	$	39.19		4,080	$	39.19
$40 – 45		3,740		4.67	$	40.37		—	$	—
$20 – 45		580,140		3.31	$	29.57		289,350	$	29.35

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

The fair value of each option granted was estimated on the date of grant using the Black-Scholes option-pricing model using the following weighted-average assumptions:

	Year Ended December 31,
	2019		2018		2017
Expected term (in years)		—		—		5.0
Expected volatility		—		—		26.1	%
Expected dividend yields		—		—		3.0	%
Risk-free interest rates		—		—		2.0	%

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, 2019:

				Weighted-		Aggregate
				average		intrinsic
	Number			grant date		value
	of shares			fair value		(in millions)
Balance at December 31, 2016		125,240			30.66
RSUs granted		70,960			34.53
RSUs vested		(36,336	)		26.99
RSUs cancelled/forfeited/expired		(66,200	)		32.63
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	$	15.0