Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
NET INCOME	$ 29,532	$ 17,756	$ 69,733	$ 64,531
OTHER COMPREHENSIVE INCOME (LOSS)
Net unrealized gains (losses) on available-for-sale securities, net of unrealized gains and losses relating to hedged interest rate risk included in net income	(5,822)	10,897	(25,314)	6,371
Non-credit portion of other-than-temporary impairment losses on held-to-maturity securities	0	0	0	(195)
Reclassification adjustment for non-credit portion of other-than-temporary impairment losses recognized as credit losses in net income	0	0	0	351
Accretion of non-credit portion of other-than-temporary impairment losses to the carrying value of held-to-maturity securities	2,044	2,367	6,144	7,609
Postretirement benefit plan
Prior service cost	0	0	(211)	0
Amortization of prior service credit included in net periodic benefit cost	(5)	(8)	(13)	(26)
Amortization of net actuarial gain included in net periodic benefit cost	(6)	(9)	(18)	(26)
Total other comprehensive income (loss)	(3,789)	13,247	(19,412)	14,084
TOTAL COMPREHENSIVE INCOME	$ 25,743	$ 31,003	$ 50,321	$ 78,615