Variable Interest Entities - Carrying Amounts and Classification of Significant Variable Interests (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 3,555,571	$ 2,545,750	$ 2,521,319	$ 1,503,257
Non-marketable and other securities	627,469	622,552
Amortization Method Qualified Affordable Housing Project Investments	148,036	112,447
Accrued interest receivable and other assets	849,761	672,688
Total assets	50,754,287	44,683,660
Total liabilities	46,556,989	40,906,623
Maximum exposure to loss in unconsolidated VIEs	323,284	314,810
Qualified Affordable Housing Project Investments, Commitment	90,974	58,095
Consolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	7,555	11,469
Non-marketable and other securities	190,129	196,140
Accrued interest receivable and other assets	169	294
Total assets	197,853	207,903
Total liabilities	445	517
Maximum exposure to loss in unconsolidated VIEs	197,400
Accrued Liabilities and Other Liabilities	445	517
Unconsolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	0	0
Non-marketable and other securities	323,284	314,810
Accrued interest receivable and other assets	0	0
Total assets	323,284	314,810
Total liabilities	$ 90,974	$ 58,095