Employee Benefit Plans Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,102	$ 1,695	$ 6,143	$ 5,086
Interest cost	4,321	4,522	12,630	13,566
Expected return on plan assets	(6,369)	(6,455)	(18,618)	(19,366)
Amortization of prior service cost	327	340	956	1,020
Amortization of losses	4,394	2,593	12,846	7,779
Net periodic benefit cost	4,775	2,695	13,957	8,085
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	227	99	664	463
Interest cost	242	257	706	729
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	6	49	18	93
Amortization of losses	156	296	455	428
Net periodic benefit cost	$ 631	$ 701	$ 1,843	$ 1,713