Borrowings - SBI Bonds (Details)	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2021 JPY (¥)	Dec. 31, 2020 JPY (¥)	Jul. 25, 2016 USD ($)	Jul. 25, 2016 JPY (¥)
Debt Instrument [Line Items]
Outstanding principal amount	$ 1,630,496,000
SBI bonds
Debt Instrument [Line Items]
Outstanding principal amount	30,722,000	$ 33,898,000
VFH | SBI bonds
Debt Instrument [Line Items]
Face amount						$ 33,100,000	¥ 3,500,000,000
Outstanding principal amount	30,700,000	33,900,000		¥ 3,500,000,000	¥ 3,500,000,000
Gain (loss) due to change in currency rates	$ (3,200,000)	$ 1,700,000	$ 300,000