Employee Benefit Plans (Defined Benefit Plan) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Amounts recognized in accumulated other comprehensive income/(loss):
Net amount recognized in accumulated other comprehensive income/(loss)	$ 256,651		$ 256,651
Qualified Pension Plans
Value of plan assets:
Beginning fair value of plan assets			195,410
Expected return on plan assets			14,445
Plan settlements			(6,416)
Employer contributions			8,780
Benefits paid			(7,702)
Ending value of plan assets	204,517		204,517
Projected benefit obligation:
Beginning projected benefit obligation			408,216
Service cost	1,653	$ 3,514	6,822	$ 11,664
Interest cost	3,702	3,862	11,146	11,788
Plan amendment			(40,049)
Plan settlements			(21,847)
Benefits paid			(7,702)
Actuarial gain			(4,768)
Ending projected benefit obligation	349,392		349,392
Funded status	(144,875)		(144,875)
Accumulated benefit obligation	349,392		349,392
Amounts recognized in the consolidated balance sheet:
Long-term liabilities	(144,875)		(144,875)
Amounts recognized in accumulated other comprehensive income/(loss):
Prior service credit	33,772		33,772
Net actuarial loss	(98,106)		(98,106)
Net amount recognized in accumulated other comprehensive income/(loss)	(64,334)		(64,334)
Post-retirement Healthcare Plans
Value of plan assets:
Beginning fair value of plan assets			0
Employer contributions			4,092
Benefits paid			(4,092)
Ending value of plan assets	0		0
Projected benefit obligation:
Beginning projected benefit obligation			741,372
Service cost	62	6,279	4,479	18,968
Interest cost	1,005	$ 7,897	6,683	$ 22,520
Plan amendment			(609,619)
Plan curtailment			(5,409)
Benefits paid			(4,092)
Actuarial gain			(27,075)
Ending projected benefit obligation	106,339		106,339
Funded status	(106,339)		(106,339)
Amounts recognized in the consolidated balance sheet:
Current liabilities	(5,166)		(5,166)
Long-term liabilities	(101,173)		(101,173)
Net amount recognized in long-term liabilities in the consolidated balance sheet	106,339		106,339
Amounts recognized in accumulated other comprehensive income/(loss):
Prior service credit	439,872		439,872
Net actuarial loss	(140,607)		(140,607)
Net amount recognized in accumulated other comprehensive income/(loss)	$ 299,265		$ 299,265