Stock-Based Compensation - Restricted Stock (Details) - Restricted stock	9 Months Ended
	Jun. 30, 2017 $ / shares shares
Restricted stock awards activity, shares
Unvested at the beginning of the period (in shares) | shares	648,000
Granted (in shares) | shares	292,112
Vested (in shares) | shares	(271,000)
Forfeited (in shares) | shares	(9,000)
Unvested at the end of the period (in shares) | shares	660,000
Restricted stock awards activity, weighted average grant date fair value
Unvested at the beginning of the period (in dollars per share) | $ / shares	$ 64.24
Granted (in dollars per share) | $ / shares	78.69
Vested (in dollars per share) | $ / shares	63.81
Forfeited (in dollars per share) | $ / shares	67.79
Unvested at the end of the period (in dollars per share) | $ / shares	$ 70.76