Joint Ventures (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended	9 Months Ended
	Mar. 31, 2017	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2016	Jun. 30, 2015	Jan. 04, 2016	Sep. 30, 2015
Cash received from formation of joint venture						$ 250,000	$ 0
Current portion of deferred income recorded in connection with joint venture		$ 6,176			$ 6,176	6,176			$ 0
Noncurrent portion of deferred income recorded in connection with joint venture		240,129			240,129	240,129			0
Income taxes payable		47,921			$ 47,921	47,921			$ 6,555
Equity interest in earnings of joint venture		$ 2,728		$ 0		$ 4,886	$ 0
Woodward and General Electric Joint Venture [Member]
Equity Method Investment, Ownership Percentage		50.00%			50.00%	50.00%
Cash received from formation of joint venture			$ 250,000
Cash to be received annually from formation of joint venture	$ 4,894
Amount of deferred income recorded in connection with joint venture								$ 250,000
Current portion of deferred income recorded in connection with joint venture		$ 6,176			$ 6,176	$ 6,176
Noncurrent portion of deferred income recorded in connection with joint venture		240,129			240,129	240,129
Income taxes payable		46,520	94,125		46,520	46,520
Deferred income tax assets			$ 94,125
Equity interest in earnings of joint venture		2,728			4,886
Cash distributions from joint venture					0
Net investment in joint venture		4,886			4,886	4,886
Accounts receivable from related party		4,426			4,426	4,426
Accounts payable to related party		3,908			3,908	$ 3,908
Woodward and General Electric Joint Venture [Member] | Sales [Member]
Amortization of deferred income recognized as an increase to sales		1,733			3,695
Sales to related party		15,136			30,151
Reduction to sales related to royalties paid to joint venture		$ 7,643			$ 14,659