Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Valuation allowance	$ 86,197		$ 107,928
Unrecognized tax benefits that would affect the effective tax rate if recognized	167,200
Undistributed earnings of foreign subsidiaries	$ 31,200
Dutch
Income Tax Contingency [Line Items]
Valuation allowance		$ 29,600
Minimum
Income Tax Contingency [Line Items]
Income Tax Statute Of Limitations Period	3 years
Maximum
Income Tax Contingency [Line Items]
Income Tax Statute Of Limitations Period	5 years
Federal
Income Tax Contingency [Line Items]
Reduction in orphan drug credit benefit due to change in tax rate	50.00%
Net operating loss carryforwards	$ 132,400
Research credit carry forward	507,292
State
Income Tax Contingency [Line Items]
Research credit carry forward	$ 112,100