Variable Interest Entities - Carrying Amounts and Classification of Significant Variable Interests (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 6,946,196	$ 3,571,539	$ 3,819,141	$ 2,923,075
Non-marketable and other equity securities	1,150,094	941,104
Accrued interest receivable and other assets	1,586,068	951,261
Total assets	68,231,233	56,927,979
Other liabilities	1,731,222	1,006,359
Total liabilities	62,182,764	51,663,136
Maximum exposure to loss in unconsolidated VIEs	655,278	568,272
Investments in qualified affordable housing projects, net	419,028	318,575
Consolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	21,418	9,058
Non-marketable and other equity securities	254,962	221,646
Accrued interest receivable and other assets	708	228
Total assets	277,088	230,932
Other liabilities	3,077	919
Total liabilities	3,077	919
Maximum exposure to loss in unconsolidated VIEs	274,000
Unconsolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	0	0
Non-marketable and other equity securities	655,278	568,272
Accrued interest receivable and other assets	0	0
Total assets	655,278	568,272
Other liabilities	276,940	205,685
Total liabilities	276,940	205,685
Maximum exposure to loss in unconsolidated VIEs	$ 655,278	$ 568,272