Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Additions to and reclassifications out of accumulated other comprehensive income (loss)
Balance at beginning of period	$ (58,788)	$ (303)	$ (29,203)	$ (13,582)
Other comprehensive income (loss) before reclassifications	(52,455)	(1,167)	(83,199)	10,244
Amount reclassified from accumulated other comprehensive income (loss)		1,146	1,159	3,014
Balance at end of period	(111,243)	(324)	(111,243)	(324)
Foreign currency translation adjustment
Additions to and reclassifications out of accumulated other comprehensive income (loss)
Balance at beginning of period	(58,788)	2,514	(28,482)	(9,680)
Other comprehensive income (loss) before reclassifications	(52,455)	(705)	(82,761)	11,489
Balance at end of period	(111,243)	1,809	(111,243)	1,809
Gains and losses on cash flow hedges
Additions to and reclassifications out of accumulated other comprehensive income (loss)
Balance at beginning of period		(2,817)	(721)	(3,902)
Other comprehensive income (loss) before reclassifications		(462)	(438)	(1,245)
Amount reclassified from accumulated other comprehensive income (loss)		1,146	1,159	3,014
Balance at end of period		$ (2,133)		$ (2,133)