Condensed Statement of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Comprehensive Income [Abstract]
Unrealized gain (loss) on investments, Changes arising during current period, tax	$ 0	$ (2,750)	$ 251	$ (9,774)
Unrealized gain (loss) on investments, Reclassification for gain included in net income, tax	592	2,057	3,589	2,193
Retirement plan actuarial losses, Reclassification for gain included in net income, tax	0	0	0	0
Retirement plan transition obligation, Reclassification for gain included in net income, tax	$ 0	$ 0	$ 0	$ 0