Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Assets:
Total assets measured at fair value	$ 133,249	$ 133,147
Liabilities:
Total liabilities measured at fair value	5,676	5,516
Money Market Funds [Member]
Assets:
Cash Equivalents, at Carrying Value	133,249	133,147
Contingent consideration [Member]
Liabilities:
Total liabilities measured at fair value	5,676	5,516
Level 1 [Member]
Assets:
Total assets measured at fair value	133,249	133,147
Liabilities:
Total liabilities measured at fair value	0	0
Level 1 [Member] | Money Market Funds [Member]
Assets:
Cash Equivalents, at Carrying Value	133,249	133,147
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:
Cash Equivalents, at Carrying Value	0	0
Level 2 [Member] | Contingent consideration [Member]
Liabilities:
Total liabilities measured at fair value	0	0
Level 3 [Member]
Assets:
Unrealized gain on foreign currency translation	2
Total assets measured at fair value	0	0
Liabilities:
Total liabilities measured at fair value	5,676	5,516
Level 3 [Member] | Money Market Funds [Member]
Assets:
Cash Equivalents, at Carrying Value	0	0
Level 3 [Member] | Contingent consideration [Member]
Liabilities:
Total liabilities measured at fair value	$ 5,676	$ 5,516