Fair Value Measurements Fair Value Measurements - Reconciliation of Contingent Consideration Measured at Fair Value (Detail) - Fair Value, Measurements, Recurring [Member] - Contingent Consideration Liability [Member] - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balances, beginning of period	$ 0	$ 0
Purchase		21,284,000
Total loss included in other income, net	218,000	218,000
Settlement	0	0
Balances, end of period	$ 21,502,000	$ 21,502,000