Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Share-based Compensation, Equity Instruments Other Than Options, Activity

The table below summarizes award activity.

	Year Ended December 31
	2020			2019			2018
	Number of Awards	Weighted average grant-date fair value		Number of Awards	Weighted average grant-date fair value		Number of Awards	Weighted average grant-date fair value
Outstanding at beginning of period	963,832	$	17.67	969,928	$	15.89	873,849	$	12.30
Granted	437,054	18.85		302,596	23.22		304,795	24.18
Converted	(278,163)	21.34		(291,064)	17.14		(205,616)	12.74
Expired	(34,100)	19.40		(7,900)	23.78		(500)	28.38
Forfeited	(3,600)	21.62		(9,728)	23.37		(2,600)	26.76
Outstanding at end of period	1,085,023	$	17.14	963,832	$	17.67	969,928	$	15.89
Vested	460,685	$	13.00	476,389	$	11.11	463,422	$	10.25

Schedule of Share-based Payment Award, Equity Instruments Other Than Options, Valuation Assumptions

The market condition awards were valued using a Monte Carlo simulation technique based on volatility over three years for the awards granted in 2020, 2019 and 2018 using daily stock prices and using the following variables:

	2020	2019	2018
Risk-free interest rate	0.7%	2.5%	2.4%
Volatility	35.0%	35.6%	33.8%