Stockholders' Equity and EPS - Reclassifications out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017		Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Related tax (benefit) expense	$ (97,351)	[1]	$ (76,877)	$ (220,412)	[1]	$ (195,508)
Net income available to common stockholders	148,620	[1]	111,081	373,296	[1]	283,219
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 losses (gains) included in net income	101		15	(384)		(11,567)
Related tax (benefit) expense	(41)		(6)	157		4,707
Net income available to common stockholders	$ 60		$ 9	$ (227)		$ (6,860)

[1] Included in income tax expense, net income available to common shareholders, earnings per common share-basic and earnings for common share-diluted, for the three and nine months ended September 30, 2017, are tax benefits recognized associated with the adoption of Accounting Standards Update (“ASU”) 2016-09, Improvements to Employee Share-Based Payment Accounting in the first quarter of 2017. This guidance was adopted on a prospective basis with no change to prior period amounts.