Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net income	$ 195,028	$ 193,044	$ 116,331
Unrealized gains on securities:
Change in unrealized securities gains arising during period	3,108	(10,201)	(38,809)
Deferred tax benefit (expense)	(1,148)	3,760	14,889
Reclassification adjustment for losses (gains) included in net income before income taxes	262	(2,373)	(104)
Deferred tax expense (benefit)	(159)	1,436	63
Total change in unrealized gains on securities, net of tax	2,063	(7,378)	(23,961)
Change in fair value cash flow hedges:
Change in unrecognized loss on cash flow hedges	(8,329)	(9,994)	67
Deferred tax benefit (expense)	3,289	3,946	(26)
Reclassification adjustment for losses included in net income before income taxes	7,107	5,869	5,234
Deferred tax expense (benefit)	(2,806)	(2,317)	(2,067)
Total change in unrecognized loss on cash flow hedges, net of tax	(739)	(2,496)	3,208
Change in pension obligation:
Change in pension obligation	(58,630)	(6,815)	49,889
Deferred tax benefit (expense)	22,959	2,669	(19,525)
Reclassification adjustment for losses included in net income	7,071	4,010	3,814
Deferred tax expense (benefit)	(2,769)	(1,570)	(1,494)
Total change in pension obligation, net of tax	(31,369)	(1,706)	32,684
Other comprehensive income (loss)	(30,045)	(11,580)	11,931
Total comprehensive income	$ 164,983	$ 181,464	$ 128,262