Significant Accounting Policies - Derivative Accounting (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Notional derivative contracts	$ 6,589,856	$ 8,557,883
CME
Derivative Instruments, Gain (Loss) [Line Items]
Notional derivative contracts	$ 5,200,000
Percent of total notional derivative contracts	94.40%
LCH
Derivative Instruments, Gain (Loss) [Line Items]
Notional derivative contracts	$ 300,000
Percent of total notional derivative contracts	5.60%
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Notional derivative contracts	$ 5,536,096	$ 8,557,883