Allocation of Consideration Transferred for Crescendo (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Jun. 30, 2014	Feb. 28, 2014 Crescendo Biosciences, Inc.
Business Acquisition [Line Items]
Other assets acquired			$ 15,826
Intangible assets			196,600
Goodwill	169,181	169,181	112,331
Total assets acquired			324,757
Deferred tax liability			44,213
Other liabilities assumed			21,594
Total net assets acquired			$ 258,950