Stockholders' Equity and EPS - Reclassifications out of AOCI (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income tax expense	$ (38,961)	$ (47,404)	$ (131,460)	$ (103,773)
Net income available to common stockholders	62,995	67,621	205,093	157,096
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	990	(219)	17,411	(949)
Income tax expense	(400)	85	(7,030)	363
Net income available to common stockholders	$ 590	$ (134)	$ 10,381	$ (586)