Stockholders’ Equity (Details)	6 Months Ended
	Mar. 31, 2016 item $ / shares shares
RSUs
Stockholders' Equity
Number of shares of common stock that each award holder has the contingent right to receive	1
Number of units awarded (in shares)	1,435,888
Vested awards to date	346,247
Expected awards vested (in shares)	464,461
Number of Shares
Balance unvested at the beginning of the period (in shares)	760,285
Granted (in shares)	381,875
Vested (in shares)	(116,137)
Forfeited (in shares)	(190,955)
Balance unvested at the end of the period (in shares)	835,068
Weighted Average Grant-Date Fair Value
Balance unvested at the beginning of the period (in dollars per share) | $ / shares	$ 47.24
Granted (in dollars per share) | $ / shares	44.69
Vested (in dollars per share) | $ / shares	46.77
Forfeited (in dollars per share) | $ / shares	44.66
Balance unvested at the end of the period (in dollars per share) | $ / shares	$ 46.72
Time-based RSUs
Stockholders' Equity
Number of units awarded (in shares)	712,651
Number of equal installments for vesting of stock awards | item	4
Performance-based RSUs
Stockholders' Equity
Number of units awarded (in shares)	723,237
Vesting period	3 years
Number of vesting criteria which have to be satisfied out of total vesting criteria | item	1
Number of vesting criteria | item	3