Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement of Income of Comprehensive Income [Abstract]
Net income	$ 134,348	$ 195,028	$ 193,044
Unrealized gains on securities:
Change in unrealized securities gains arising during period	9,566	3,108	(10,201)
Deferred tax (expense) benefit	(3,759)	(1,148)	3,760
Reclassification adjustment for losses (gains) included in net income	(2,322)	262	(2,373)
Deferred tax expense (benefit)	917	(159)	1,436
Total change in unrealized gains on securities, net of tax	4,402	2,063	(7,378)
Change in fair value of cash flow hedges:
Change in unrecognized loss on cash flow hedges	(2,779)	(8,329)	(9,994)
Deferred tax benefit	1,097	3,289	3,946
Reclassification adjustment for losses included in net income	3,095	7,107	5,869
Deferred tax benefit	(1,222)	(2,806)	(2,317)
Total change in unrecognized loss on cash flow hedges, net of tax	191	(739)	(2,496)
Change in pension obligation:
Change in pension obligation	(44,315)	(58,630)	(6,815)
Deferred tax benefit	17,354	22,959	2,669
Reclassification adjustment for losses included in net income	11,236	7,071	4,010
Deferred tax benefit	(4,400)	(2,769)	(1,570)
Total change in pension obligation, net of tax	(20,125)	(31,369)	(1,706)
Other comprehensive loss, net of tax	(15,532)	(30,045)	(11,580)
Total comprehensive income	$ 118,816	$ 164,983	$ 181,464