Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Qualified Pension
Schedule of net periodic benefit cost related to pension and post-retirement healthcare
Service cost	$ 4,633	$ 3,649	$ 13,910	$ 11,841
Interest cost	3,774	3,695	11,175	10,994
Expected return on plan assets	(3,082)	(3,356)	(9,384)	(9,887)
Amortization of actuarial loss	1,635	575	3,981	1,617
Plan settlement	52	89	1,065	445
Net periodic benefit cost	7,012	4,652	20,747	15,010
Post-retirement Healthcare
Schedule of net periodic benefit cost related to pension and post-retirement healthcare
Service cost	5,874	5,923	20,838	19,491
Interest cost	5,785	5,774	18,770	18,139
Expected return on plan assets	0	(8)	0	(25)
Amortization of actuarial loss	1,464	1,398	5,934	4,762
Plan settlement	0	0	0	0
Net periodic benefit cost	$ 13,123	$ 13,087	$ 45,542	$ 42,367