Stockholders' Equity and EPS - Reclassifications out of AOCI (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income tax expense	$ 58,917	$ 26,401
Net income available to common stockholders	91,301	40,891
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	(60)	45
Income tax expense	(24)	18
Net income available to common stockholders	$ (36)	$ 27