Basis of Presentation - Reserves (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Sep. 30, 2015
Accounts receivable reserves
Total accounts receivable reserves	$ 127,188	$ 106,859
Promotional program incentive allowances
Accounts receivable reserves
Total accounts receivable reserves	102,758	84,088
Allowance for sales returns
Accounts receivable reserves
Total accounts receivable reserves	18,282	17,080
Allowance for doubtful accounts
Accounts receivable reserves
Total accounts receivable reserves	2,632	2,600
Other accounts receivable allowances
Accounts receivable reserves
Total accounts receivable reserves	$ 3,516	$ 3,091