Variable Interest Entities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Subordinated Borrowing [Line Items]
Federal tax credits recognized in tax expense	$ 520	$ 550	$ 1,550	$ 1,560
Investment tax credits	0	$ 320	9,480	$ 3,320
Investment carrying amount	8,097,486		8,097,486		$ 8,096,289
Unfunded capital and other commitments	7,211,126		7,211,126		7,126,825
Maximum exposure to loss, unconsolidated VIEs	50,048		50,048		50,319
Variable interest entity, primary beneficiary
Subordinated Borrowing [Line Items]
Investment carrying amount	66,910		66,910		59,080
Unfunded capital and other commitments	0		0		0
Variable interest entity, not primary beneficiary
Subordinated Borrowing [Line Items]
Investment carrying amount	55,546		55,546		35,968
Unfunded capital and other commitments	$ 51,428		$ 51,428		$ 29,670