Summary of Significant Accounting Policies - Impact of Recent Accounting Standards and Interpretations (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2016 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment	$ 0
Benefit to income tax expense	475
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment	67,041
ASU No. 2016-09 | Retained earnings | New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment	$ 67,000