Significant Accounting Policies - Schedule of Basic Weighted Average Shares Reconciles to Diluted Weighted Average Shares Outstanding (Details) - shares shares in Thousands	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
Accounting Policies [Abstract]
Basic weighted average common shares outstanding (in shares)	76,128	76,562	76,539	76,419	76,283	76,309	76,220	76,115	76,412	76,232	75,803
Dilutive effect of stock options, restricted stock and performance share units (in shares)									1,151	1,101	955
Diluted weighted average common shares outstanding (in shares)	77,100	77,709	77,704	77,739	77,597	77,523	77,320	76,894	77,563	77,333	76,758