Net Income (Loss) Per Share of Common Stock - Schedule of Computation of Basic and Diluted Net Income (Loss) Per Share of Common Stock (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
BASIC AND DILUTED:
Net income (loss) attributable to common stockholders	$ (128,828)	$ 5,609
BASIC:
Net income (loss) attributable to common stockholders	$ (128,828)	$ 5,609
Weighted-average common shares outstanding – basic	926,230	869,627
Net income (loss) per share attributable to common stockholders – basic	$ (0.14)	$ 0.01
DILUTED:
Weighted-average common shares outstanding – basic	926,230	869,627
Weighted-average common shares outstanding – diluted	926,230	893,774
Net income (loss) per share attributable to common stockholders – diluted	$ (0.14)	$ 0.01
Common Class A [Member]
BASIC AND DILUTED:
Net income (loss) attributable to common stockholders	$ (128,828)	$ 5,047
Weighted-average common shares outstanding	926,230
Net income (loss) per share attributable to common stockholders	$ (0.14)
BASIC:
Net income (loss) attributable to common stockholders	$ (128,828)	$ 5,047
Weighted-average common shares outstanding – basic		782,370
Net income (loss) per share attributable to common stockholders – basic		$ 0.01
DILUTED:
Net income (loss) attributable to common stockholders - basic		$ 5,047
Net income (loss) attributable to common stockholders – diluted		$ 5,609
Weighted-average common shares outstanding – basic		782,370
Weighted-average common shares outstanding – diluted		893,774
Net income (loss) per share attributable to common stockholders – diluted		$ 0.01
Common Class A [Member] | Stock Options and Employee Stock Purchase Plan [Member]
DILUTED:
Weighted-average effect of dilutive securities		10,166
Common Class A [Member] | Restricted Stock Units (ZSUs) [Member]
DILUTED:
Weighted-average effect of dilutive securities		12,605
Common Class A [Member] | Performance Based Restricted Stock Units (ZSUs) [Member]
DILUTED:
Weighted-average effect of dilutive securities		1,376
Common Class A [Member] | Class C Convert To Class A [Member]
DILUTED:
Reallocation of net income (loss) as a result of common stock class conversion		$ 132
Conversion of common stock class		20,517
Common Class A [Member] | Class B convert to Class A [Member]
DILUTED:
Reallocation of net income (loss) as a result of common stock class conversion		$ 430
Conversion of common stock class		66,740
Common Class B [Member]
BASIC AND DILUTED:
Net income (loss) attributable to common stockholders		$ 430
BASIC:
Net income (loss) attributable to common stockholders		$ 430
Weighted-average common shares outstanding – basic		66,740
Net income (loss) per share attributable to common stockholders – basic		$ 0.01
DILUTED:
Net income (loss) attributable to common stockholders - basic		$ 430
Reallocation of net income (loss) to Class B and Class C shares		41
Net income (loss) attributable to common stockholders – diluted		$ 471
Weighted-average common shares outstanding – basic		66,740
Weighted-average common shares outstanding – diluted		75,036
Net income (loss) per share attributable to common stockholders – diluted		$ 0.01
Common Class B [Member] | Stock Options and Employee Stock Purchase Plan [Member]
DILUTED:
Weighted-average effect of dilutive securities		8,296
Common Class C [Member]
BASIC AND DILUTED:
Net income (loss) attributable to common stockholders		$ 132
BASIC:
Net income (loss) attributable to common stockholders		$ 132
Weighted-average common shares outstanding – basic		20,517
Net income (loss) per share attributable to common stockholders – basic		$ 0.01
DILUTED:
Net income (loss) attributable to common stockholders - basic		$ 132
Reallocation of net income (loss) to Class B and Class C shares		(3)
Net income (loss) attributable to common stockholders – diluted		$ 129
Weighted-average common shares outstanding – basic		20,517
Weighted-average common shares outstanding – diluted		20,517
Net income (loss) per share attributable to common stockholders – diluted		$ 0.01