Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net Income	$ 41,783	$ 39,227
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized gain (loss) on securities	13,933	125
Reclassification adjustment for securities (gains) losses included in net income	(944)	(1,608)
Non-credit related unrealized gain (loss) on other-than-temporarily impaired debt securities	189	1,083
Unrealized gain on derivative financial instruments	34	34
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax	2,144	0
Amortization (accretion) of net unrecognized pension and postretirement plan items	96	328
Other Comprehensive Income (Loss)	15,452	(38)
Total Comprehensive Income	$ 57,235	$ 39,189