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	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
BASIC:
Net income (loss) attributable to common stockholders	$ (108,173)	$ (121,510)	$ (225,900)
Weighted-average common shares outstanding-basic	878,827	913,511	874,509
Basic net income (loss) per share	$ (0.12)	$ (0.13)	$ (0.26)
DILUTED:
Weighted-average common shares outstanding-basic	878,827	913,511	874,509
Weighted-average common shares outstanding-diluted	878,827	913,511	874,509
Diluted net income (loss) per share	$ (0.12)	$ (0.13)	$ (0.26)
Common Class A [Member]
BASIC:
Net income (loss) attributable to common stockholders	$ (92,988)	$ (103,628)	$ (189,732)
Weighted-average common shares outstanding-basic	755,460	779,071	734,493
Basic net income (loss) per share	$ (0.12)	$ (0.13)	$ (0.26)
DILUTED:
Net income (loss) attributable to common stockholders-basic	$ (92,988)	$ (103,628)	$ (189,732)
Net income (loss) attributable to common stockholders-diluted	$ (108,173)	$ (121,510)	$ (225,901)
Weighted-average common shares outstanding-basic	755,460	779,071	734,493
Weighted-average common shares outstanding-diluted	878,827	913,511	874,509
Diluted net income (loss) per share	$ (0.12)	$ (0.13)	$ (0.26)
Common Class B [Member]
BASIC:
Net income (loss) attributable to common stockholders	$ (12,660)	$ (15,153)	$ (30,869)
Weighted-average common shares outstanding-basic	102,850	113,923	119,499
Basic net income (loss) per share	$ (0.12)	$ (0.13)	$ (0.26)
DILUTED:
Net income (loss) attributable to common stockholders-basic	$ (12,660)	$ (15,153)	$ (30,869)
Net income (loss) attributable to common stockholders-diluted	$ (12,660)	$ (15,153)	$ (30,869)
Weighted-average common shares outstanding-basic	102,850	113,923	119,499
Weighted-average common shares outstanding-diluted	102,850	113,923	119,499
Diluted net income (loss) per share	$ (0.12)	$ (0.13)	$ (0.26)
Common Class C [Member]
BASIC:
Net income (loss) attributable to common stockholders	$ (2,525)	$ (2,729)	$ (5,300)
Weighted-average common shares outstanding-basic	20,517	20,517	20,517
Basic net income (loss) per share	$ (0.12)	$ (0.13)	$ (0.26)
DILUTED:
Net income (loss) attributable to common stockholders-basic	$ (2,525)	$ (2,729)	$ (5,300)
Net income (loss) attributable to common stockholders-diluted	$ (2,525)	$ (2,729)	$ (5,300)
Weighted-average common shares outstanding-basic	20,517	20,517	20,517
Weighted-average common shares outstanding-diluted	20,517	20,517	20,517
Diluted net income (loss) per share	$ (0.12)	$ (0.13)	$ (0.26)
Class C Convert To Class A [Member] | Common Class A [Member]
DILUTED:
Reallocation of net income (loss) as a result of common stock class conversion	$ (2,525)	$ (2,729)	$ (5,300)
Conversion of common stock class	20,517	20,517	20,517
Class B convert to Class A [Member] | Common Class A [Member]
DILUTED:
Reallocation of net income (loss) as a result of common stock class conversion	$ (12,660)	$ (15,153)	$ (30,869)
Conversion of common stock class	102,850	113,923	119,499