Variable Interest Entities - Additional Information (Details) $ in Thousands		Jun. 30, 2015 USD ($) entity	Dec. 31, 2014 USD ($)		Jun. 30, 2014 USD ($)	[1]	Dec. 31, 2013 USD ($)
Variable Interest Entity [Line Items]
Number of deconsolidated entities | entity		16
Assets		$ (40,236,118)	$ (39,339,950)
Total equity		$ (3,189,472)	(4,051,734)	[1]	$ (3,933,194)		$ (3,074,693)
Number of consolidated entities | entity		5
Non-marketable and other securities	[2]	$ 645,506	$ 1,728,140
Consolidated
Variable Interest Entity [Line Items]
Assets		(223,557)
Non-marketable and other securities		200,695
Cumulative-Effect Adjustment, Deconsolidation of Variable Interest Entity
Variable Interest Entity [Line Items]
Assets		1,100,000
Total equity		1,200,000
Qualified affordable housing projects of | Consolidated
Variable Interest Entity [Line Items]
Non-marketable and other securities		122,500
Unfunded commitments | Consolidated
Variable Interest Entity [Line Items]
Non-marketable and other securities		$ 63,600

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