Restatement - Narrative (Details) (USD $)	3 Months Ended														6 Months Ended				9 Months Ended				12 Months Ended
	Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Dec. 31, 2012		Dec. 31, 2011		Mar. 31, 2013		Mar. 31, 2012		Jun. 30, 2013	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2010
(Overstatement) understatement of accrued postretirement benefits	$ 22,989,000		$ 22,878,000		$ 22,815,000		$ 22,526,000		$ 19,239,000		$ 19,172,000		$ 19,027,000		$ 22,878,000		$ 19,172,000		$ 22,989,000		$ 19,239,000		$ 16,076,000	$ 22,526,000		$ 18,996,000
(Overstatement) understatement of other comprehensive income	(1,306,000)		(7,157,000)		2,979,000		(36,972,000)		(5,211,000)		(3,813,000)		(7,280,000)		(4,178,000)		(11,093,000)		(5,484,000)		(16,304,000)		(6,480,000)	(53,150,000)		(29,355,000)		(31,297,000)
Adjustments
(Overstatement) understatement of accrued postretirement benefits	(12,404,000)	[1]	(12,280,000)	[1]	(12,155,000)	[1]	(12,031,000)	[2]	(5,476,000)	[1]	(5,180,000)	[1]	(4,884,000)	[1]	(12,280,000)	[1]	(5,180,000)	[1]	(12,404,000)	[1]	(5,476,000)	[1]		(12,031,000)	[2]	(4,589,000)	[2]
(Overstatement) understatement of other comprehensive income	109,000	[3]	137,000	[3]	105,000	[3]	8,503,000	[3]	290,000	[3]	297,000	[3]	304,000	[3]	242,000	[3]	601,000	[3]	351,000	[3]	891,000	[3]		9,520,000	[4]	9,151,000	[4],[5]	(2,557,000)	[4],[5]
Retiree Medical Plan | Adjustments
(Overstatement) understatement of accrued postretirement benefits							(20,700,000)																	(20,700,000)		(11,200,000)
(Overstatement) understatement of other comprehensive income																								19,200,000	[4]	11,100,000	[4]
Death Benefit Plan | Adjustments
(Overstatement) understatement of accrued postretirement benefits							8,100,000																	8,100,000		6,400,000
(Overstatement) understatement of other comprehensive income																								(2,200,000)	[4]	(800,000)	[4]
Understatement of the Cash Surrender Value of life insurance							$ 2,200,000																	$ 2,200,000		$ 2,100,000

[1] For details see the introduction section included in Note 2.

[2] For details see the introduction section included elsewhere in this Note 2.

[3] See summary table of the impact of the restatement corrections and immaterial adjustments on the consolidated statements of operations and comprehensive income (loss) included in Note 2.

[4] (1) See summary table of the impact of the restatement corrections and immaterial adjustments on the consolidated statements of operations and comprehensive income (loss) included elsewhere in this Note 2.

[5] See summary table of the impact of the restatement corrections and immaterial adjustments on the consolidated statements of operations and comprehensive income (loss) included elsewhere in this Note 2.