Fair Value Measurements - Additional Information (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Derivative Instrument Detail [Abstract]
Net gain on sale of investments	$ 23,400,000
Investment securities outstanding	0
Unrealized gain (loss) on interest rate cash flow hedges, pretax, accumulated other comprehensive income (loss)	36,700,000	$ 43,700,000
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	$ 10,500,000