Stockholders' Equity and EPS - Reclassifications out of AOCI (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income tax expense	$ (33,582)	$ (29,968)	$ (92,499)	$ (56,369)
Net income available to common stockholders	50,797	48,584	142,098	89,475
Reclassification out of Accumulated Other Comprehensive Income | (Losses) 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	16,480	(775)	16,421	(730)
Income tax expense	(6,653)	296	(6,630)	278
Net income available to common stockholders	$ 9,827	$ (479)	$ 9,791	$ (452)