Employee Benefits (Net Periodic Benefit Cost) (Details) (Other Postretirement Benefit Plans, Defined Benefit, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 2,988	$ 3,558	$ 3,395
Interest cost	5,379	6,664	6,492
Expected return on plan assets	(1,823)	(1,529)	(1,499)
Prior service benefit	(5,927)	(2,869)	(2,869)
Net gain	(39)	(175)	0
Net periodic benefit cost	$ 578	$ 5,649	$ 5,519