Employee Benefit Plans Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,102	$ 1,695	$ 4,042	$ 3,390
Interest cost	4,321	4,522	8,309	9,044
Expected return on plan assets	(6,369)	(6,455)	(12,248)	(12,910)
Amortization of prior service cost	327	340	629	680
Amortization of losses	4,394	2,593	8,451	5,186
Net periodic benefit cost	4,775	2,695	9,183	5,390
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	227	182	437	364
Interest cost	242	236	465	472
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	6	22	12	44
Amortization of losses	156	66	299	132
Net periodic benefit cost	$ 631	$ 506	$ 1,213	$ 1,012