Employee Benefit Plans (Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule of net periodic benefit cost related to pension and post-retirement healthcare
Other post-employment benefit and pension expense	$ (67,428)	$ (57,568)	$ (174,142)	$ (116,926)
Qualified Pension Plans
Schedule of net periodic benefit cost related to pension and post-retirement healthcare
Service cost	1,847	1,653	5,033	6,822
Interest cost	3,719	3,702	11,360	11,146
Expected return on plan assets	(3,848)	(3,688)	(11,516)	(10,911)
Amortization of actuarial loss	1,343	1,570	4,040	5,311
Amortization of prior service cost	(760)	(863)	(2,281)	(2,070)
Plan curtailment	0	(4,207)	0	(4,207)
Plan settlement	477	110	477	717
Net periodic benefit cost	2,778	(1,723)	7,113	6,808
Less capitalized portion	(161)	(137)	(440)	(469)
Other post-employment benefit and pension expense	2,617	(1,860)	6,673	6,339
Post-retirement Healthcare Plans
Schedule of net periodic benefit cost related to pension and post-retirement healthcare
Service cost	9	62	91	4,479
Interest cost	929	1,005	2,945	6,683
Expected return on plan assets	0	0	0	0
Amortization of actuarial loss	18,118	32,775	81,526	80,649
Amortization of prior service cost	(89,101)	(89,550)	(265,377)	(215,076)
Plan curtailment	0	0	0	0
Plan settlement	0	0	0	0
Net periodic benefit cost	(70,045)	(55,708)	(180,815)	(123,265)
Less capitalized portion	0	0	0	0
Other post-employment benefit and pension expense	$ (70,045)	$ (55,708)	$ (180,815)	$ (123,265)