Fair Value Measurements - Changes in Estimated Fair Value of Contingent Consideration Liabilities (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2016	$ 4,689,000	$ 5,175,000
Change in fair value of acquisition contingencies	0
Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2016	4,689,000	5,175,000
Cash payments	(486,000)
Balance at March 31, 2017	4,689,000
Commitments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2016	4,689,000	5,175,000
Commitments [Member] | Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2016	$ 4,689,000	$ 5,175,000