Summary of Significant Accounting Policies - Product Revenue (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) deliverable	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) $ / shares
Accounting Policies [Abstract]
Gross U.S. product sales	$ 748,839	$ 561,255	$ 190,512
Provision for U.S. product sales allowances and accruals:
Contractual adjustments	229,686	161,665	73,262
Governmental rebates	86,983	57,774	7,252
Total provision for U.S. product sales allowances and accruals	316,669	219,439	80,514
U.S. product sales, net	$ 432,170	341,816	109,998
Rebate period	3 months
Prompt payment discount (percent)	2.00%
Prompt payment period	30 days
Accrued percentage of prompt payment discount (percent)	100.00%
Inventory [Line Items]
Reduction of reserve for product returns			$ 1,800
Increase in net income per basic share (in USD per share) | $ / shares			$ 0.08
Increase in net income per diluted share (in USD per share) | $ / shares			$ 0.07
Number of service revenue deliverables | deliverable	2
Prepayment term for storage of newborn cord blood and tissue units (years)	18 years
Medicaid rebate reserve
Inventory [Line Items]
Reduction of estimated Medicaid rebate reserve	$ 6,100
Feraheme
Inventory [Line Items]
Expiration period (in years)	5 years
Makena
Inventory [Line Items]
Expiration period (in years)	3 years
Makena | Medicaid rebate reserve
Inventory [Line Items]
Reduction of estimated Medicaid rebate reserve		4,000
Makena | Chargeback reserves
Inventory [Line Items]
Reduction of estimated Medicaid rebate reserve		$ 1,900