Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator:
Allocation of undistributed earnings	$ (119,265)	$ (67,748)	$ (165,092)	$ (110,296)
Denominator:
Weighted-average common shares outstanding (in shares)	134,132	128,241	133,073	126,864
Basic net loss per share attributable to common shockholders (in dollars per share)	$ (0.89)	$ (0.53)	$ (1.24)	$ (0.87)
Numerator:
Allocation of undistributed earnings for basic computation	$ (119,265)	$ (67,748)	$ (165,092)	$ (110,296)
Diluted net loss per share attributable to common stockholders (in dollars per share)	$ (0.89)	$ (0.53)	$ (1.24)	$ (0.87)
Add:
Number of shares used in diluted calculation (in shares)	134,132	128,241	133,073	126,864
Class A Common Stock [Member]
Numerator:
Allocation of undistributed earnings	$ (105,430)	$ (59,469)	$ (145,784)	$ (96,649)
Denominator:
Weighted-average common shares outstanding (in shares)	118,573	112,569	117,509	111,167
Basic net loss per share attributable to common shockholders (in dollars per share)	$ (0.89)	$ (0.53)	$ (1.24)	$ (0.87)
Numerator:
Allocation of undistributed earnings for basic computation	$ (105,430)	$ (59,469)	$ (145,784)	$ (96,649)
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares	$ (13,835)	$ (8,279)	$ (19,308)	$ (13,647)
Diluted net loss per share attributable to common stockholders (in dollars per share)	$ (0.89)	$ (0.53)	$ (1.24)	$ (0.87)
Allocation of undistributed earnings	$ (119,265)	$ (67,748)	$ (165,092)	$ (110,296)
Add:
Conversion of Class B to Class A common shares outstanding (in shares)	15,559	15,672	15,564	15,697
Number of shares used in diluted calculation (in shares)	134,132	128,241	133,073	126,864
Class B Common Stock [Member]
Numerator:
Allocation of undistributed earnings	$ (13,835)	$ (8,279)	$ (19,308)	$ (13,647)
Denominator:
Weighted-average common shares outstanding (in shares)	15,559	15,672	15,564	15,697
Basic net loss per share attributable to common shockholders (in dollars per share)	$ (0.89)	$ (0.53)	$ (1.24)	$ (0.87)
Numerator:
Allocation of undistributed earnings for basic computation	$ (13,835)	$ (8,279)	$ (19,308)	$ (13,647)
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares	$ 0	$ 0	$ 0	$ 0
Diluted net loss per share attributable to common stockholders (in dollars per share)	$ (0.89)	$ (0.53)	$ (1.24)	$ (0.87)
Allocation of undistributed earnings	$ (13,835)	$ (8,279)	$ (19,308)	$ (13,647)
Add:
Conversion of Class B to Class A common shares outstanding (in shares)	0	0	0	0
Number of shares used in diluted calculation (in shares)	15,559	15,672	15,564	15,697