Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 7,307	$ 6,890	$ 125,735	$ 128,286
Other comprehensive income:
Reclassifications of net losses on derivative instruments (net of tax of $(277), $(278), $(833) and $(834), respectively)	392	393	1,175	1,176
Benefit plans reclassifications of actuarial losses and prior service costs (net of tax of $(92), $(67), $(275) and $(206), respectively)	128	95	388	288
Other comprehensive income	520	488	1,563	1,464
Comprehensive income	$ 7,827	$ 7,378	$ 127,298	$ 129,750