Earnings per Share - Weighted-Average Shares Outstanding for Computation of Basic and Diluted Income per Common Share (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Earnings Per Share [Abstract]
Basic method	163,992,427	172,974,491	[1]	172,524,061	[1]
Dilutive stock options	820,001	1,234,274		0
Diluted method	164,812,428	174,208,765	[1]	172,524,061	[1]
Unvested stock awards				$ 0

[1] ¹ Reclassified to conform with current presentation (see Notes C and E). 2017 revenue is presented net of $58.9 million of transportation, gathering and processing costs as historically shown prior to the adoption of ASC 606 on January 1, 2018. See Notes to Consolidated Financial Statements, page 58.