Earnings per Share Earnings per Share (Details) - shares	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted average common shares—basic	45,747,659	45,850,288	45,920,307	45,779,966	45,721,160	45,721,155	45,717,697	45,570,495	45,824,555	45,682,627	45,407,316
Weighted average common shares—diluted	46,085,202	46,166,558	46,200,757	46,229,337	45,721,160	46,029,361	45,922,416	45,908,958	46,170,464	45,990,252	45,407,316
Restricted Shares [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Incremental common shares attributable to dilutive effect of share-based payment arrangements									242,204	241,974	0
Stock Options [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Incremental common shares attributable to dilutive effect of share-based payment arrangements									103,705	65,651	0