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 |
6 Months Ended |
---|---|
Jun. 30, 2015
USD ($)
| |
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] | |
Beginning balance | $ 6,796 |
Changes in fair value | 2,188 |
Reclassification to accrued expenses | (1,000) |
Ending balance | $ 7,984 |