Variable Interest Entities - Carrying Amounts and Classification of Significant Variable Interests (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 9,020,925	$ 3,571,539	$ 2,712,101	$ 2,923,075
Non-marketable and other equity securities	1,079,749	941,104
Accrued interest receivable and other assets	1,465,081	951,261
Total assets	63,773,739	56,927,979
Other liabilities	1,540,476	1,006,359
Total liabilities	58,067,564	51,663,136
Maximum exposure to loss in unconsolidated VIEs	642,882	568,272
Investments in qualified affordable housing projects, net	394,046	318,575
Other liabilities consisting of unfunded commitments related to qualified affordable housing projects	266,761	205,685
Consolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	7,387	9,058
Non-marketable and other equity securities	250,028	221,646
Accrued interest receivable and other assets	469	228
Total assets	257,884	230,932
Other liabilities	2,421	919
Total liabilities	2,421	919
Maximum exposure to loss in unconsolidated VIEs	255,500
Unconsolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	0	0
Non-marketable and other equity securities	642,882	568,272
Accrued interest receivable and other assets	0	0
Total assets	642,882	568,272
Other liabilities	266,761	205,685
Total liabilities	266,761	205,685
Maximum exposure to loss in unconsolidated VIEs	$ 642,882	$ 568,272