Stockholders' Equity (Details) - USD ($) $ / shares in Units, shares in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Aug. 01, 2018
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Amount of stock repurchase authorization							$ 400,000,000
Treasury Stock, Shares, Acquired		4.1
Payments for Repurchase of Common Stock		$ 140,600,000				$ 25,400,000
Amount remaining under stock repurchase authorization		$ 234,900,000
Dividends, Common Stock [Abstract]
Cash dividends declared per common share (in dollars per share)		$ 0.15	$ 0.125	$ 0.125	$ 0.125	$ 0.125
Cash dividends paid per common share (in dollars per share)		$ 0.15	$ 0.125	$ 0.125	$ 0.125	$ 0.125
Subsequent Event [Member]
Dividends, Common Stock [Abstract]
Cash dividends declared per common share (in dollars per share)	$ 0.15
Forestar Group [Member]
Class of Stock [Line Items]
Equity Securities Registered, Value			$ 500,000,000