Employee Benefit Plans (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 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	1,549	5,086	4,647
Defined Benefit Plan, Interest Cost	4,522	4,435	13,566	13,305
Defined Benefit Plan, Expected Return on Plan Assets	(6,455)	(5,412)	(19,366)	(16,238)
Defined Benefit Plan Amortization Of Prior Service Cost	340	414	1,020	1,243
Defined Benefit Plan Amortization Of Plan Amendment	0	0	0	0
Defined Benefit Plan, Amortization of Losses (Gains)	2,593	1,614	7,779	4,842
Defined Benefit Plan, Net Periodic Benefit Cost	2,695	2,600	8,085	7,799
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	99	148	463	440
Defined Benefit Plan, Interest Cost	257	258	729	772
Defined Benefit Plan, Expected Return on Plan Assets	0	0	0	0
Defined Benefit Plan Amortization Of Prior Service Cost	49	21	93	65
Defined Benefit Plan Amortization Of Plan Amendment	0	(637)	0	(5,421)
Defined Benefit Plan, Amortization of Losses (Gains)	296	459	428	3,415
Defined Benefit Plan, Net Periodic Benefit Cost	$ 701	$ 249	$ 1,713	$ (729)