Earnings per Common Share - Reconciliation of Weighted Average Number of Common Shares Outstanding (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Weighted average common shares outstanding – basic (in shares)	143,499	70,049	133,965	69,990
Dilutive effect of share-based awards (in shares)	2,975	0	2,772	0
Weighted average common shares outstanding – diluted (in shares)	146,474	70,049	136,737	69,990