Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pension Plans Defined Benefit Member
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Service Cost	$ 1,532	$ 1,415
Defined Benefit Plan Interest Cost	980	890
Defined Benefit Plan Expected Return On Plan Assets	734	644
Defined Benefit Plan Amortization Of Prior Service Cost Credit	99	7
Defined Benefit Plan Amortization Of Gains Losses	(275)	(188)
Total	2,152	1,856
Other Postretirement Benefit Plans Defined Benefit Member
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Service Cost	279	212
Defined Benefit Plan Interest Cost	259	220
Defined Benefit Plan Expected Return On Plan Assets	0	0
Defined Benefit Plan Amortization Of Prior Service Cost Credit	0	0
Defined Benefit Plan Amortization Of Gains Losses	(88)	(59)
Total	$ 626	$ 491