Earnings per Share Earnings per Share (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted average common shares—basic	45,578,815	45,779,966
Weighted average common shares—diluted	45,992,182	46,229,337
Restricted Stock Units (RSUs) [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Incremental common shares attributable to share-based payment arrangements	333,020	358,583
Stock Options [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Incremental common shares attributable to share-based payment arrangements	80,347	90,788