Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net Income	$ 40,582	$ 39,891	$ 79,809	$ 78,023
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized gain (loss) on securities	(36,958)	(10,704)	(36,833)	(6,120)
Reclassification adjustment for securities (gains) losses included in net income	(1,862)	(999)	(3,470)	(1,812)
Non-credit related unrealized gain (loss) on other-than-temporarily impaired debt securities	355	(172)	1,438	(37)
Unrealized gain on derivative financial instruments	34	34	68	68
Amortization (accretion) of net unrecognized pension and postretirement plan items	328	214	656	428
Other Comprehensive Income (Loss)	(38,103)	(11,627)	(38,141)	(7,473)
Total Comprehensive Income	$ 2,479	$ 28,264	$ 41,668	$ 70,550