Employee Benefit Plans (Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule of net periodic benefit cost related to pension and post-retirement healthcare
Other post-employment benefit and pension expense	$ (53,486)	$ (52,460)	$ (106,714)	$ (59,358)
Qualified Pension Plans
Schedule of net periodic benefit cost related to pension and post-retirement healthcare
Service cost	1,593	1,823	3,185	5,169
Interest cost	3,821	3,633	7,641	7,444
Expected return on plan assets	(3,834)	(3,658)	(7,668)	(7,223)
Amortization of actuarial loss	1,349	1,886	2,698	3,741
Amortization of prior service cost	(761)	(863)	(1,521)	(1,207)
Plan settlement	0	607	0	607
Net periodic benefit cost	2,168	3,428	4,335	8,531
Less capitalized portion	(148)	(251)	(279)	(332)
Other post-employment benefit and pension expense	2,020	3,177	4,056	8,199
Post-retirement Healthcare Plans
Schedule of net periodic benefit cost related to pension and post-retirement healthcare
Service cost	41	62	82	4,417
Interest cost	1,008	1,013	2,016	5,678
Expected return on plan assets	0	0	0	0
Amortization of actuarial loss	31,704	32,838	63,407	47,874
Amortization of prior service cost	(88,259)	(89,550)	(176,275)	(125,526)
Plan settlement	0	0	0	0
Net periodic benefit cost	(55,506)	(55,637)	(110,770)	(67,557)
Less capitalized portion	0	0	0	0
Other post-employment benefit and pension expense	$ (55,506)	$ (55,637)	$ (110,770)	$ (67,557)