Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Accumulated other comprehensive income (loss), net of tax [Abstract]
Pension costs	$ 567,427		$ 575,163
Postretirement costs	42,403		41,811
Deferred taxes on pension and OPEB costs	(227,283)		(230,161)
All other	149		150
Accumulated other comprehensive loss, net of tax	382,696		386,963
Other comprehensive income (loss), before tax [Abstract]
Amortization of pension and postretirement costs	7,145	3,334
All other	0	(750)
Other comprehensive income (loss)	7,145	2,584
Other comprehensive income (loss), tax [Abstract]
Amortization of pension and postretirement costs	2,878	1,199
All other	0	(270)
Other comprehensive income (loss)	2,878	929
Other comprehensive income (loss), net of tax [Abstract]
Amortization of pension and postretirement costs	4,267	2,135
All other	0	(480)
Other comprehensive income (loss)	$ 4,267	$ 1,655	$ (159,069)