Property and Equipment - Additional Information (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Property Plant And Equipment [Line Items]
Depreciation expense	$ 1,200,000	$ 700,000	$ 2,300,000	$ 1,100,000
Capitalized internal-use software	3,200,000	1,300,000	5,000,000	2,400,000
Share-based compensation capitalized in internal-use software development costs	1,100,000	100,000	1,125,000	85,000
Amortization expense of capitalized internal-use software	1,000,000	500,000	1,700,000	1,000,000
Carrying value of capitalized internal-use software	10,200,000		10,200,000		6,800,000
Construction in progress	$ 3,400,000		$ 3,400,000		$ 300,000