Borrowings - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	6 Months Ended
	Jan. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Junior subordinated debentures		$ 538,000
Debt Maturity, Start Year		Jan. 01, 2027
Debt Maturity, End Year		Dec. 31, 2033
Description of variable rate basis	Secured Overnight Financing Rate ("SOFR")
Short-term borrowings		$ 7,907,884	$ 3,554,951
Additional borrowing capacity		14,900,000
Available line of credit		16,100,000
Long-term borrowings		$ 7,416,638	$ 3,964,537
5.053% Fixed Rate Senior Notes Due to Mature in January 2034 [Member]
Debt Instrument [Line Items]
Senior notes	$ 1,000,000
Senior notes maturity date	Jan. 31, 2034
Interest rate of debt instrument	5.053%
Variable interest rate of debt instrument	1.85%
4.65% Fixed Rate Senior Notes Due to Mature in January 2026 [Member]
Debt Instrument [Line Items]
Senior notes	$ 1,300,000
Senior notes maturity date	Jan. 31, 2026
Interest rate of debt instrument	4.65%
4.70% Fixed Rate Senior Notes Due to Mature in January 2028 [Member]
Debt Instrument [Line Items]
Senior notes	$ 1,200,000
Senior notes maturity date	Jan. 31, 2028
Interest rate of debt instrument	4.70%