Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010
Pension Benefits [Member]
Components of net periodic cost:
Service cost	$ 127	$ 115	$ 254	$ 230
Interest cost	588	564	1,176	1,129
Expected return on plan assets	(99)	(96)	(198)	(192)
Recognized net actuarial loss (gain)	265	362	529	724
Amortization of prior service cost	185	178	370	355
Curtailment loss	3,117		3,117
Net periodic cost	4,183	1,123	5,248	2,246
Retiree Health Care Benefits [Member]
Components of net periodic cost:
Service cost	8	10	15	20
Interest cost	59	59	118	118
Recognized net actuarial loss (gain)	(18)	(21)	(36)	(42)
Amortization of prior service cost	35	35	70	69
Curtailment loss
Net periodic cost	$ 84	$ 83	$ 167	$ 165