Employee Benefit Plans (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of qualified non-contributory defined benefit pension plans			4
Pension Contributions			$ 0
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	0		0
Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	1,695	1,452	3,390	3,098
Defined Benefit Plan, Interest Cost	4,522	4,291	9,044	8,870
Defined Benefit Plan, Expected Return on Plan Assets	(6,455)	(5,416)	(12,910)	(10,826)
Defined Benefit Plan Amortization Of Prior Service Cost	340	518	680	829
Defined Benefit Plan Amortization Of Plan Amendment	0	0
Defined Benefit Plan, Amortization of Gains (Losses)	2,593	1,130	5,186	3,228
Defined Benefit Plan, Net Periodic Benefit Cost	2,695	1,975	5,390	5,199
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	182	146	364	292
Defined Benefit Plan, Interest Cost	236	257	472	514
Defined Benefit Plan, Expected Return on Plan Assets	0	0	0	0
Defined Benefit Plan Amortization Of Prior Service Cost	22	22	44	44
Defined Benefit Plan Amortization Of Plan Amendment	0	(2,392)	0	(4,784)
Defined Benefit Plan, Amortization of Gains (Losses)	66	1,478	132	2,956
Defined Benefit Plan, Net Periodic Benefit Cost	$ 506	$ (489)	$ 1,012	$ (978)