Summary of Significant Accounting Policies - Financial Assets by Major Security Type and Contingent Consideration Liability Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets
Cash and cash equivalents, fair value disclosure	$ 6,806	$ 17,717
Total assets	6,806	37,291
Liabilities
Contingent consideration liability	2,800	30,800
Total liabilities	2,800	30,800
Money Market Funds [Member]
Assets
Cash and cash equivalents, fair value disclosure	6,806	12,674
Corporate Debt Securities [Member]
Assets
Cash and cash equivalents, fair value disclosure	0	24,617
Level 1 [Member]
Assets
Total assets	6,806	12,674
Liabilities
Contingent consideration liability	0	0
Total liabilities	0	0
Level 1 [Member] | Money Market Funds [Member]
Assets
Cash and cash equivalents, fair value disclosure	6,806	12,674
Level 1 [Member] | Corporate Debt Securities [Member]
Assets
Cash and cash equivalents, fair value disclosure	0	0
Level 2 [Member]
Assets
Total assets	0	24,617
Liabilities
Contingent consideration liability	0	0
Total liabilities	0	0
Level 2 [Member] | Money Market Funds [Member]
Assets
Cash and cash equivalents, fair value disclosure	0	0
Level 2 [Member] | Corporate Debt Securities [Member]
Assets
Cash and cash equivalents, fair value disclosure	0	24,617
Level 3 [Member]
Assets
Total assets	0	0
Liabilities
Contingent consideration liability	2,800	30,800
Total liabilities	2,800	30,800
Level 3 [Member] | Money Market Funds [Member]
Assets
Cash and cash equivalents, fair value disclosure	0	0
Level 3 [Member] | Corporate Debt Securities [Member]
Assets
Cash and cash equivalents, fair value disclosure	$ 0	$ 0