Employee Benefit Plans - Components of Net Periodic Benefit Cost and Amounts Recognized in Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2012
Defined Benefit Pension Plans
Components of net periodic benefit cost
Service cost	$ 119	$ 124
Interest cost	1,449	1,525
Expected return on plan assets	(1,660)	(1,703)
Amortization of net (gain) loss	387	342
Amortization of prior service cost (credit)	5	5
Net periodic benefit cost	300	293
Weighted average assumptions used to determine benefit obligations
Discount rate	4.60%		5.60%
Expected long-term return on plan assets	8.00%		8.30%
Rate of compensation increase	0.00%		3.00%
Other Postretirement Benefits
Components of net periodic benefit cost
Service cost	409	409
Interest cost	330	330
Expected return on plan assets	0	0
Amortization of net (gain) loss	(199)	(199)
Amortization of unrecognized transition (asset) obligation	0	0
Amortization of prior service cost (credit)	(58)	(58)
Net periodic benefit cost	$ 482	$ 482
Weighted average assumptions used to determine benefit obligations
Discount rate	5.46%		5.46%