Stockholders' Equity and EPS - Reclassifications out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Related tax expense (benefit)	$ (53,584)	$ (63,066)
Net income available to common stockholders	79,174	88,516
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	746	(2,596)
Related tax expense (benefit)	(304)	1,048
Net income available to common stockholders	$ 442	$ (1,548)