Shareholders' Equity (Capped Call Transaction) (Details) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2018 shares	Jun. 30, 2018 $ / shares shares	Sep. 30, 2017 shares	Oct. 01, 2016 USD ($) shares $ / shares
Class of Stock [Line Items]
Settlement of capped calls (in shares)		0
Capped Calls
Class of Stock [Line Items]
Additional paid in capital, capped calls | $				$ 7,935
Capped calls initial equivalent shares (in shares)				2,282,000
Capped calls settled, percentage			10.00%
Settlement of capped calls (in shares)			12,000
Capped Calls | Minimum
Class of Stock [Line Items]
Option indexed to issuer's equity, strike price (in dollars per share) | $ / shares				$ 50.40
Capped Calls | Maximum
Class of Stock [Line Items]
Option indexed to issuer's equity, strike price (in dollars per share) | $ / shares				$ 58.80
Capped Call Agreements
Class of Stock [Line Items]
Capped calls outstanding equivalent shares (in shares)	2,054,000
Capped Call Agreements | Minimum
Class of Stock [Line Items]
Option indexed to issuer's equity, strike price (in dollars per share) | $ / shares		$ 50.40
Capped Call Agreements | Maximum
Class of Stock [Line Items]
Option indexed to issuer's equity, strike price (in dollars per share) | $ / shares		$ 57.97
Capped Call Agreements | Common Stock | Minimum
Class of Stock [Line Items]
Common stock to be received and retired under capped calls (in shares)		0
Capped Call Agreements | Common Stock | Maximum
Class of Stock [Line Items]
Common stock to be received and retired under capped calls (in shares)		268,000