Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Assets:
Total assets measured at fair value	$ 178,103	$ 3,057
Liabilities:
Total liabilities measured at fair value	5,608	5,756
Contingent consideration [Member]
Liabilities:
Total liabilities measured at fair value	5,608	5,756
Level 1 [Member]
Assets:
Total assets measured at fair value	178,103	3,057
Liabilities:
Total liabilities measured at fair value	0	0
Level 1 [Member] | Money Market Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash Equivalents, at Carrying Value	178,103	3,057
Assets:
Total assets measured at fair value	178,103
Level 1 [Member] | Contingent consideration [Member]
Liabilities:
Total liabilities measured at fair value	0	0
Level 2 [Member]
Assets:
Total assets measured at fair value	0	0
Liabilities:
Total liabilities measured at fair value	0	0
Level 2 [Member] | Money Market Funds [Member]
Assets:
Total assets measured at fair value	0	0
Level 2 [Member] | Contingent consideration [Member]
Liabilities:
Total liabilities measured at fair value	0	0
Level 3 [Member]
Assets:
Total assets measured at fair value	0	0
Liabilities:
Total liabilities measured at fair value	5,608	5,756
Level 3 [Member] | Money Market Funds [Member]
Assets:
Total assets measured at fair value	0	0
Level 3 [Member] | Contingent consideration [Member]
Liabilities:
Total liabilities measured at fair value	$ 5,608	$ 5,756