Stockholders' Equity (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Amount of stock repurchase authorization			$ 1,000,000,000.0
Treasury Stock, Shares, Acquired		3,000,000.0
Payments for Repurchase of Common Stock		$ 163,100,000				$ 140,600,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 732,600,000
Dividends, Common Stock [Abstract]
Cash dividends declared per common share (in dollars per share)		$ 0.175	$ 0.15	$ 0.15	$ 0.15	$ 0.15
Cash dividends paid per common share (in dollars per share)		$ 0.175	$ 0.15	$ 0.15	$ 0.15	$ 0.15
Common Stock, Shares, Issued		393,014,557	392,172,821
Subsequent Event [Member]
Dividends, Common Stock [Abstract]
Cash dividends declared per common share (in dollars per share)	$ 0.175
Forestar Group [Member]
Class of Stock [Line Items]
Equity Securities Registered, Value							$ 500,000,000
Dividends, Common Stock [Abstract]
Common Stock, Shares, Issued			6,000,000.0
Shares Issued, Price Per Share			$ 17.50
Common Stock Available for Issuance, Value Remaining		$ 394,300,000