Accumulated Other Comprehensive Income (Tables)

6 Months Ended

Mar. 31, 2016

Equity [Abstract]

Schedule of Changes in Accumulated Other Comprehensive Income

The tables below present changes in AOCI, net of tax, during the three and six months ended March 31, 2016 and 2015:

	Postretirement Benefit Plans			Derivative Instruments			Total
Three Months Ended March 31, 2016
AOCI - December 31, 2015	$	(9,116	)	$	(2,143	)	$	(11,259	)
Net losses on IRPAs	—			(18,820		)	(18,820		)
Reclassifications of benefit plan actuarial losses and prior service cost	160			—			160
Reclassifications of net losses on IRPAs	—			356			356
AOCI - March 31, 2016	$	(8,956	)	$	(20,607	)	$	(29,563	)
Three Months Ended March 31, 2015
AOCI - December 31, 2014	$	(6,180	)	$	(1,479	)	$	(7,659	)
Reclassifications of benefit plan actuarial losses and prior service cost	129			—			129
Reclassifications of net losses on IRPAs	—			392			392
AOCI - March 31, 2015	$	(6,051	)	$	(1,087	)	$	(7,138	)

	Postretirement Benefit Plans			Derivative Instruments			Total
Six Months Ended March 31, 2016
AOCI - September 30, 2015	$	(9,276	)	$	(4,410	)	$	(13,686	)
Net losses on IRPAs	—			(16,943		)	(16,943		)
Reclassifications of benefit plan actuarial losses and prior service costs	320			—			320
Reclassifications of net losses on IRPAs	—			746			746
AOCI - March 31, 2016	$	(8,956	)	$	(20,607	)	$	(29,563	)
Six Months Ended March 31, 2015
AOCI - September 30, 2014	$	(6,311	)	$	(1,870	)	$	(8,181	)
Reclassifications of benefit plan actuarial losses and prior service costs	260			—			260
Reclassifications of net losses on IRPAs	—			783			783
AOCI - March 31, 2015	$	(6,051	)	$	(1,087	)	$	(7,138	)