Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

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

The table below summarizes award activity.

	Year Ended December 31
	2018				2017				2016
	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	873,849		$	12.30	1,040,569		$	9.97	1,157,659		$	7.52
Granted	304,795		24.18		243,940		17.52		314,060		15.47
Converted	(205,616	)	12.74		(320,810	)	9.47		(329,200	)	7.32
Expired	(500	)	28.38		(82,050	)	9.22		(92,750	)	7.44
Forfeited	(2,600	)	26.76		(7,800	)	13.55		(9,200	)	10.23
Outstanding at end of period	969,928		$	15.89	873,849		$	12.30	1,040,569		$	9.97
Vested	463,422		$	10.25	441,424		$	7.61	472,294		$	6.60

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 2018, 2017 and 2016 using daily stock prices and using the following variables:

	2018	2017	2016
Risk-free interest rate	2.4%	1.7%	1.1%
Volatility	33.8%	34.7%	36.9%