Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Defined Benefit Pension Plans [Member]
Schedule Of Components Of Net Periodic Credit
Service cost	$ 1,167	$ 931	$ 2,335	$ 1,862
Interest cost	4,386	4,752	8,771	9,504
Expected return on plan assets	(12,202)	(13,310)	(24,404)	(26,620)
Amortization of accumulated other comprehensive income:
Prior service cost	308	308	616	616
Actuarial losses	4,443	2,569	8,885	5,138
Total credit	(1,898)	(4,750)	(3,797)	(9,500)
Other Postretirement Benefit Plans [Member]
Schedule Of Components Of Net Periodic Credit
Service cost	39	33	79	64
Interest cost	507	573	1,014	1,147
Amortization of accumulated other comprehensive income:
Prior service cost	(4,042)	(4,043)	(8,085)	(8,085)
Actuarial losses	1,919	2,138	3,838	4,275
Total credit	$ (1,577)	$ (1,299)	$ (3,154)	$ (2,599)