Fair Value of Assets Acquired and Liabilities Assumed - Medistem, Inc. (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 06, 2014 Medistem, Inc. Scenario, Plan
Business Acquisition [Line Items]
Cash			$ 8
Total assets acquired			8
Accounts payable			644
Accrued compensation and benefits			85
Other accrued expenses			150
Total liabilities assumed			879
Net liabilities assumed			(871)
Goodwill	39,689	13,823	25,866
Total consideration			$ 24,995