Stockholders' Equity and EPS - Reclassifications out of AOCI (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Related tax expense (benefit)	[1]	$ (57,017)	$ (40,207)	$ (175,057)	[2]	$ (137,431)
Net income available to common stockholders	[1]	81,733	63,977	256,392	[2]	205,880
Reclassification out of Accumulated Other Comprehensive Income | Gains on investment securities, net
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Reclassification adjustment for (gains) losses included in net income		(13)	990	(2,750)		17,411
Related tax expense (benefit)		6	(400)	1,111		(7,030)
Net income available to common stockholders		$ (7)	$ 590	$ (1,639)		$ 10,381

[1] Prior period amounts have been revised to reflect the retrospective application of new accounting guidance adopted in the first quarter of 2015 related to our investments in qualified affordable housing projects (ASU 2014-01). See Note 1— "Basis of Presentation" of the "Notes to Interim Consolidated Financial Statements" under Part I, Item 1 in this report.

[2] Amounts for the nine months ended September 30, 2015, have been revised to reflect the retrospective application of new accounting guidance adopted in the second quarter of 2015 related to our consolidated variable interest entities (ASU 2015-02). Amounts prior to January 1, 2015 have not been revised for the adoption of this guidance. See Note 1— "Basis of Presentation” of the “Notes to Interim Consolidated Financial Statements (unaudited)” under Part I, Item 1 of this report for additional details.