Equity Awards (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Schedule of summary of option activity

The following table summarizes the option activity:

	Year Ended December 31,
	2019				2018				2017
	Shares		Weighted- Average Exercise Price		Shares		Weighted- Average Exercise Price		Shares		Weighted- Average Exercise Price
Outstanding:
Beginning of year	1,115,324		$	29.02	1,479,236		$	27.81	2,234,699		$	22.84
Granted	—		$	—	—		$	—	205,244		$	42.24
Exercised	(459,415	)	$	26.87	(308,025	)	$	22.01	(898,218	)	$	18.53
Forfeited	(12,058	)	$	36.84	(55,887	)	$	35.69	(62,489	)	$	30.80
End of year	643,851		$	30.41	1,115,324		$	29.02	1,479,236		$	27.81
Exercisable, end of year	590,340		$	29.34	814,421		$	26.46	846,371		$	22.35

Schedule of value of the options granted was estimated at the date of grant using the Black-Scholes-Merton

The value of the options granted was estimated at the date of grant using the Black-Scholes-Merton option pricing model using the following assumptions:

	Year Ended December 31,
	2017
Risk-free interest rate	1.97	%
Dividend yield	2.85	%
Expected share price volatility	27.39	%
Expected life	5.0 years

Schedule of summary of RSU activity

The following table summarizes RSU activity:

	Year Ended December 31,
	2019				2018				2017
	Shares		Weighted- Average Grant Date Fair Value		Shares		Weighted- Average Grant Date Fair Value		Shares		Weighted- Average Grant Date Fair Value
Unvested, beginning of year	300,142		$	39.22	178,882		$	37.93	196,800		$	24.38
Granted	197,078		$	42.56	227,481		$	39.74	137,034		$	42.20
Vested	(134,407	)	$	37.99	(83,384	)	$	37.61	(132,764	)	$	24.24
Forfeited	(22,445	)	$	41.32	(22,837	)	$	40.21	(22,188	)	$	26.06
Unvested, end of year	340,368		$	41.50	300,142		$	39.22	178,882		$	37.93

Schedule of summary of amount of expense and related tax benefit

The amount of expense and related tax benefit is summarized below:

	Year Ended December 31,
	2019		2018		2017
	(in thousands)
Share based compensation expense	$	7,178	$	6,228	$	7,688
U.S. tax benefit on share based compensation expense	$	872	$	716	$	2,093