Income Taxes - Reconciliation of the Federal Statutory Tax Rate to the Total Tax Provision (Detail)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Federal income taxes computed at the statutory rate	34.00%	34.00%
State income taxes, net of federal benefit	3.30%	3.30%
Research & development tax refunds & credits	(5.60%)	(33.60%)
Dividend received deduction	(6.10%)	(3.00%)
Domestic international sales corporation benefits	(4.20%)	(1.80%)
Tax-exempt interest income	(1.80%)	(1.40%)
Other, net	1.70%	(3.70%)
Effective income tax rate	21.30%	(6.20%)