Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands				3 Months Ended		6 Months Ended	12 Months Ended
	Feb. 02, 2016	Dec. 21, 2015	Nov. 04, 2015	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2017	Sep. 30, 2016
DTECH
Assets and liabilities measured at fair value on a recurring basis
Volatility earning metrics						21.00%	18.00%
H4 Global
Assets and liabilities measured at fair value on a recurring basis
Period for contingent consideration contracts			5 years
Initial measurement recognized at acquisition			$ 1,900
TeraLogics
Assets and liabilities measured at fair value on a recurring basis
Volatility earning metrics						16.00%	17.00%
Initial measurement recognized at acquisition		$ 33,900
GATR
Assets and liabilities measured at fair value on a recurring basis
Volatility earning metrics						16.00%	17.00%
Period for contingent consideration contracts	12 months
Initial measurement recognized at acquisition	$ 220,500
Level 2
Debt instruments
Fair Value				$ 199,900		$ 199,900	$ 210,000
Carrying value				200,800		200,800	201,000
Level 3
Assets and liabilities measured at fair value on a recurring basis
Balance at the Beginning period				7,453	$ 11,267	11,267
Cash paid to seller					(2,500)
Total remeasurement (gain) loss recognized in earnings				(880)	(1,314)
Balance at the ending period				6,573	7,453	6,573	11,267
Level 3 | DTECH
Assets and liabilities measured at fair value on a recurring basis
Balance at the Beginning period				1,300	2,000	2,000
Total remeasurement (gain) loss recognized in earnings				100	(700)
Balance at the ending period				1,400	1,300	1,400	2,000
Level 3 | H4 Global
Assets and liabilities measured at fair value on a recurring basis
Balance at the Beginning period				453	567	567
Total remeasurement (gain) loss recognized in earnings				20	(114)
Balance at the ending period				473	453	473	567
Level 3 | GATR
Assets and liabilities measured at fair value on a recurring basis
Balance at the Beginning period				2,800	3,200	3,200
Total remeasurement (gain) loss recognized in earnings				(1,300)	(400)
Balance at the ending period				1,500	2,800	1,500	3,200
Level 3 | Contract extensions | TeraLogics
Assets and liabilities measured at fair value on a recurring basis
Balance at the Beginning period				1,500	1,400	1,400
Total remeasurement (gain) loss recognized in earnings				100	100
Balance at the ending period				1,600	1,500	1,600	1,400
Level 3 | Revenue Targets | TeraLogics
Assets and liabilities measured at fair value on a recurring basis
Balance at the Beginning period				1,400	4,100	4,100
Cash paid to seller					(2,500)
Total remeasurement (gain) loss recognized in earnings				200	(200)
Balance at the ending period				1,600	$ 1,400	1,600	4,100
Assets and liabilities measured at fair value
Assets
Cash equivalents				81,195		81,195	57,455
Marketable securities				18,843		18,843	12,996
Current derivative assets				1,952		1,952	14,770
Noncurrent derivative assets				821		821	1,201
Marketable securities in rabbi trust				136		136	4
Total assets measured at fair value				102,947		102,947	86,426
Liabilities
Current derivative liabilities				2,260		2,260	13,752
Noncurrent derivative liabilities				821		821	1,334
Total liabilities measured at fair value				9,654		9,654	26,353
Assets and liabilities measured at fair value | DTECH
Liabilities
Noncurrent contingent consideration to seller				1,400		1,400	2,000
Assets and liabilities measured at fair value | H4 Global
Liabilities
Noncurrent contingent consideration to seller				473		473	567
Assets and liabilities measured at fair value | GATR
Liabilities
Noncurrent contingent consideration to seller				1,500		1,500	3,200
Assets and liabilities measured at fair value | Contract extensions | TeraLogics
Liabilities
Noncurrent contingent consideration to seller				1,600		1,600	1,400
Assets and liabilities measured at fair value | Revenue Targets | TeraLogics
Liabilities
Noncurrent contingent consideration to seller				1,600		1,600	4,100
Assets and liabilities measured at fair value | Level 1
Assets
Cash equivalents				81,195		81,195	57,455
Marketable securities in rabbi trust				136		136	4
Total assets measured at fair value				81,331		81,331	57,459
Assets and liabilities measured at fair value | Level 2
Assets
Marketable securities				18,843		18,843	12,996
Current derivative assets				1,952		1,952	14,770
Noncurrent derivative assets				821		821	1,201
Total assets measured at fair value				21,616		21,616	28,967
Liabilities
Current derivative liabilities				2,260		2,260	13,752
Noncurrent derivative liabilities				821		821	1,334
Total liabilities measured at fair value				3,081		3,081	15,086
Assets and liabilities measured at fair value | Level 3
Liabilities
Total liabilities measured at fair value				6,573		6,573	11,267
Assets and liabilities measured at fair value | Level 3 | DTECH
Liabilities
Noncurrent contingent consideration to seller				1,400		1,400	2,000
Assets and liabilities measured at fair value | Level 3 | H4 Global
Liabilities
Noncurrent contingent consideration to seller				473		473	567
Assets and liabilities measured at fair value | Level 3 | GATR
Liabilities
Noncurrent contingent consideration to seller				1,500		1,500	3,200
Assets and liabilities measured at fair value | Level 3 | Contract extensions | TeraLogics
Liabilities
Noncurrent contingent consideration to seller				1,600		1,600	1,400
Assets and liabilities measured at fair value | Level 3 | Revenue Targets | TeraLogics
Liabilities
Noncurrent contingent consideration to seller				$ 1,600		$ 1,600	$ 4,100