Fair Value Measurements - Changes in Estimated Fair Value of Contingent Consideration Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value of acquisition contingencies	$ 0	$ 0	$ 42
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2014		5,607		$ 5,756
Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2014		5,607		5,756
Cash payments		(129)
Unrealized gain on foreign currency translation		(20)
Balance at September 30, 2015		5,607
Commitments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2014		5,607		5,756
Commitments [Member] | Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2014		$ 5,607		$ 5,756