Convertible Notes, Net - Summary of Outstanding Convertible Senior Notes (Parenthetical) (Detail)	3 Months Ended
Mar. 31, 2019 USD ($) $ / shares
5.25% Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, conversion price	$ 34.56
5.25% Convertible Senior Notes [Member] \| Class A Common Stock [Member]
Debt Instrument [Line Items]
Convertible Notes, debt conversion, principal amount \| $	$ 1,000
Debt instrument, conversion price	$ 0
4.38% Convertible Senior Notes [Member] \| Class A Common Stock [Member]
Debt Instrument [Line Items]
Convertible Notes, debt conversion, principal amount \| $	$ 1,000
Debt instrument, conversion price	$ 0
4.75% Convertible Senior Notes Issued In March 2018 [Member] \| Class A Common Stock [Member]
Debt Instrument [Line Items]
Debt instrument, conversion price	36.23
Debt instrument, conversion price	0
4.38% Convertible Senior Notes Issued in May 2017 [Member] \| Class A Common Stock [Member]
Debt Instrument [Line Items]
Debt instrument, conversion price	35.67
Debt instrument, conversion price	$ 0

The amount of the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586

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- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031898-161870

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- Definition

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- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

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