BUSINESS (Detail) $ / shares in Units, $ in Millions				1 Months Ended	3 Months Ended			6 Months Ended		7 Months Ended	13 Months Ended
	Jan. 17, 2018 shares	Jan. 17, 2018 shares	Jan. 08, 2018 shares	Jan. 31, 2018 shares	Jun. 30, 2018 shares	Mar. 31, 2018 shares	Jun. 30, 2017 shares	Jun. 30, 2018 segment	Jun. 30, 2017 shares	Dec. 31, 2018 USD ($) $ / shares shares	Jan. 31, 2018 public_offering shares
Subsidiary, Sale of Stock [Line Items]
Number of reporting segments | segment								4
Repurchase of common stock (in shares)					0		0		0
Class A Common Stock
Subsidiary, Sale of Stock [Line Items]
Number of shares						28,700,000
Class A Common Stock | Public Stock Offering
Subsidiary, Sale of Stock [Line Items]
Number of public offerings completed | public_offering											7
Number of shares											80,200,000
Class B Common Stock
Subsidiary, Sale of Stock [Line Items]
Repurchase of common stock (in shares)	7,600,000	3,800,000	3,800,000	7,600,000
Scenario, Forecast [Member] | AV Homes
Subsidiary, Sale of Stock [Line Items]
Business acquisition, share price (in dollars per share) | $ / shares										$ 21.50
Cash purchase price of acquisition | $										$ 480
Total proration of cash to stock, cash percentage										58.80%
Total proration of cash to stock, stock percentage										41.20%
Business combination, expected equity interest owned by acquiree shareholders										10.00%
Scenario, Forecast [Member] | Payment To Acquiree Option One | AV Homes | Class A Common Stock
Subsidiary, Sale of Stock [Line Items]
Cash paid per acquiree share | $ / shares										$ 21.50
Entity shares issuable per acquiree share										0.9793
Scenario, Forecast [Member] | Payment To Acquiree Option Two | AV Homes | Class A Common Stock
Subsidiary, Sale of Stock [Line Items]
Cash paid per acquiree share | $ / shares										$ 12.64
Entity shares issuable per acquiree share										0.4034