Summary of Tax Returns Periods Subject to Examination by Federal, State and Foreign Tax Authorities (Detail)	12 Months Ended
	Dec. 31, 2020
United States | Earliest Tax Year
Income Tax Examination [Line Items]
Fiscal year subject to examination	2017
United States | Latest Tax Year
Income Tax Examination [Line Items]
Fiscal year subject to examination	2020
Sweden | Earliest Tax Year
Income Tax Examination [Line Items]
Fiscal year subject to examination	2013
Sweden | Latest Tax Year
Income Tax Examination [Line Items]
Fiscal year subject to examination	2020