Weighted Average Shares Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted Average Shares Outstanding [Line Items]
Basic (in shares)	52,304,190	54,073,407	54,191,013
Dilutive effect of:
Diluted (in shares)	52,831,606	54,605,298	54,631,313
Stock options [Member]
Dilutive effect of:
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	127,562	46,450	262,336
Stock options [Member]
Dilutive effect of:
Shares attributable to share-based payment arrangements (in shares)	260,240	258,052	166,986
Performance share awards [Member]
Dilutive effect of:
Shares attributable to share-based payment arrangements (in shares)	267,176	273,839	273,314