Variable Interest Entities - Carrying Amounts and Classification of Significant Variable Interests (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 7,066,883	$ 3,571,539	$ 2,619,384	$ 2,923,075
Non-marketable and other equity securities	974,979	941,104
Accrued interest receivable and other assets	1,260,899	951,261
Total assets	60,160,285	56,927,979
Other liabilities	1,432,928	1,006,359
Total liabilities	54,676,462	51,663,136
Maximum exposure to loss in unconsolidated VIEs	591,260	568,272
Investments in qualified affordable housing projects, net	339,900	318,575
Other liabilities consisting of unfunded commitments related to qualified affordable housing projects	223,206	205,685
Consolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	4,660	9,058
Non-marketable and other equity securities	224,136	221,646
Accrued interest receivable and other assets	764	228
Total assets	229,560	230,932
Other liabilities	1,975	919
Total liabilities	1,975	919
Maximum exposure to loss in unconsolidated VIEs	227,600
Unconsolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	0	0
Non-marketable and other equity securities	591,260	568,272
Accrued interest receivable and other assets	0	0
Total assets	591,260	568,272
Other liabilities	223,206	205,685
Total liabilities	223,206	205,685
Maximum exposure to loss in unconsolidated VIEs	$ 591,260	$ 568,272