Employee Benefit Plans - Amortization Schedule (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Amortization of Net (Gain) Loss Calculation
Amortization years		11 years 10 months 24 days
Retiree Medical Plan
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit) [Roll Forward]
Net Prior Service Cost (Credit), beginning of period	$ (19,234)
Annual Amortization	1,757
Net Prior Service Cost (Credit), end of period	(17,477)	(19,234)
Amortization of Net (Gain) Loss Calculation
Net (gain) loss	(12,087)	(3,941)
Asset (gains)/losses not yet recognized in market related value of assets	0	0
Net (gain) loss subject to amortization	(12,087)	(3,941)
Defined Benefit Plan, Corridor	872	1,527
Net (gain)/loss in excess of corridor	(11,215)	(2,414)
Amortization years	11 years 1 month 3 days
Other Postretirement Benefit Plans, Defined Benefit Plan Established January 1, 2008 [Member]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit) [Roll Forward]
Net Prior Service Cost (Credit), beginning of period	(1,653)
Annual Amortization	230
Years Remaining	7 years 2 months 12 days
Curtailment	0
Net Prior Service Cost (Credit), end of period	(1,423)
Other Postretirement Benefit Plans, Defined Benefit Plan Established July 1, 2012 [Member]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit) [Roll Forward]
Net Prior Service Cost (Credit), beginning of period	(17,581)
Annual Amortization	1,527
Years Remaining	11 years 6 months
Curtailment	0
Net Prior Service Cost (Credit), end of period	(16,054)
Death Benefit Plan
Amortization of Net (Gain) Loss Calculation
Net (gain) loss	1,850	2,231
Asset (gains)/losses not yet recognized in market related value of assets	0	0
Net (gain) loss subject to amortization	1,850	2,231
Defined Benefit Plan, Corridor	(798)	(806)
Net (gain)/loss in excess of corridor	$ 1,052	$ 1,425
Amortization years	8 years 0 months 15 days	8 years 9 months 7 days