Adjustment to additional paid in capital resulting from the recognition of convertible debt instruments as two separate components - a debt component and an equity component. This bifurcation may result in a basis difference associated with the liability component that represents a temporary difference for purposes of applying accounting for income taxes. The initial recognition of deferred taxes for the tax effect of that temporary difference is as an adjustment to additional paid in capital.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 25
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=51819886&loc=SL6014347-161799

Debt - Narrative (Detail)		1 Months Ended	3 Months Ended		9 Months Ended
Debt - Narrative (Detail)	May 15, 2020 USD ($) Vote shares	May 31, 2020 USD ($) shares	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) day	Sep. 30, 2019 USD ($)	Sep. 25, 2020 USD ($)	May 19, 2020 USD ($)	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Increased inventory under credit facilities			$ 193,300,000		$ 193,300,000				$ 836,600,000
Increased borrowings under credit facilities			114,300,000		114,300,000				691,500,000
Gain on partial extinguishment			0	$ 0	6,391,000	$ 0
Class C Capital Stock
Debt Instrument [Line Items]
Shares received in unwinding of capped call transactions (in shares) \| shares	317,865	317,865
Value based on trading price of Class C capital stock at time of unwind	$ 14,800,000	$ 14,800,000
Convertible Debt
Debt Instrument [Line Items]
Aggregate Principal Amount			2,384,664,000		2,384,664,000
Unamortized Debt Discount and Debt Issuance Costs			539,070,000		$ 539,070,000				463,348,000
2024 and 2026 Notes \| Convertible Debt
Debt Instrument [Line Items]
Debt instrument, threshold consecutive trading days \| day					30
Debt Instrument, convertible threshold percentage					130.00%
2.75% convertible senior notes due 2025 \| Convertible Debt
Debt Instrument [Line Items]
Debt instrument, convertible threshold trading days	20				20
Debt instrument, threshold consecutive trading days \| Vote	30
Debt Instrument, convertible threshold percentage	130.00%
Aggregate Principal Amount	$ 500,000,000.0		$ 565,000,000		$ 565,000,000			$ 65,000,000.0
Stated Interest Rate	2.75%		2.75%		2.75%			2.75%
Net proceeds from issuance	$ 553,300,000
Remaining consideration allocated to equity component	$ 154,800,000
Repurchase price percentage of principal amount	100.00%
Unamortized Debt Discount and Debt Issuance Costs	$ 3,300,000		$ 156,677,000		$ 156,677,000				0
2.00% convertible senior notes due 2021 \| Convertible Debt
Debt Instrument [Line Items]
Aggregate Principal Amount			$ 265,330,000		$ 265,330,000
Stated Interest Rate			2.00%		2.00%
Repurchased amount		194,700,000
Cash paid for repurchase		194,700,000
Aggregate purchase price		230,900,000
Fair value of liability component		172,900,000
Remaining consideration allocated to equity component		58,000,000.0
Reduction to long-term debt		179,300,000
Reduction to additional paid-in capital		58,000,000.0
Gain on partial extinguishment		$ 6,400,000
Unamortized Debt Discount and Debt Issuance Costs			$ 16,067,000		$ 16,067,000				44,498,000
2.00% convertible senior notes due 2021 \| Convertible Debt \| Class C Capital Stock
Debt Instrument [Line Items]
Shares issued in debt conversion \| shares		753,936
Line of Credit \| Mortgages Segment
Debt Instrument [Line Items]
Maximum Borrowing Capacity			150,000,000		150,000,000
Comerica Bank \| Line of Credit \| Mortgages Segment
Debt Instrument [Line Items]
Maximum Borrowing Capacity			75,000,000		75,000,000		$ 75,000,000.0
Increase to maximum borrowing capacity							$ 25,000,000.0
Citibank, N.A.
Debt Instrument [Line Items]
Repurchase agreement, committed amount			25,000,000.0		25,000,000.0
Citibank, N.A. \| Mortgages Segment
Debt Instrument [Line Items]
Short-term debt			58,859,000		58,859,000				$ 394,000
Citibank, N.A. \| Line of Credit \| Mortgages Segment
Debt Instrument [Line Items]
Maximum Borrowing Capacity			$ 75,000,000		$ 75,000,000