Accumulated Other Comprehensive Loss (Schedule of Reclassification out of Accumulated Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of investments	$ 0	$ 6,039	$ 0	$ 9,160
Provision for income taxes	(682)	(2,910)	(1,608)	(4,553)
Consolidated net income	1,131	8,958	4,367	14,404
Amount Reclassified from Accumulated Other Comprehensive Loss | Unrealized holding gains on available-for-sale investments
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of investments	0	4,333	0	8,002
Provision for income taxes	0	(1,624)	0	(2,997)
Consolidated net income	$ 0	$ 2,709	$ 0	$ 5,005