Comprehensive income (Details 1) (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Accumulated other comprehensive income (loss), net consisted of unrealized gains (losses)
Beginning Balance	$ (205,220)	$ (335,997)
Net gain (loss) during period	(23,549)	138,800
Ending Balance	(228,769)	(197,197)
Investment securities with OTTI [Member]
Accumulated other comprehensive income (loss), net consisted of unrealized gains (losses)
Beginning Balance	(87,053)	(76,772)
Net gain (loss) during period	11,663	(798)
Ending Balance	(75,390)	(77,570)
Investment securities all other [Member]
Accumulated other comprehensive income (loss), net consisted of unrealized gains (losses)
Beginning Balance	2,332	(142,853)
Net gain (loss) during period	(39,555)	137,564
Ending Balance	(37,223)	(5,289)
Cash flow hedges [Member]
Accumulated other comprehensive income (loss), net consisted of unrealized gains (losses)
Beginning Balance	393	674
Net gain (loss) during period	(141)	(141)
Ending Balance	252	533
Defined benefit plans [Member]
Accumulated other comprehensive income (loss), net consisted of unrealized gains (losses)
Beginning Balance	(120,892)	(117,046)
Net gain (loss) during period	4,288	2,175
Ending Balance	(116,604)	(114,871)
Foreign currency translation adjustment [Member]
Accumulated other comprehensive income (loss), net consisted of unrealized gains (losses)
Net gain (loss) during period	196
Ending Balance	$ 196