Fair value measurements - Roll-Forward of Fair Value of the Company's Contingent Consideration Obligations (Detail) - Significant unobservable inputs (Level 3) [Member] - Contingent consideration obligations [Member] $ in Thousands |
3 Months Ended |
---|---|
Mar. 31, 2017
USD ($)
| |
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] | |
Beginning balance | $ 7,756 |
Changes in fair value | 1,433 |
Ending balance | $ 9,189 |