Note 12. Stockholders' Equity (Detail) - Dividends Declared During the Period (USD $) In Thousands, except Per Share data, unless otherwise specified	1 Months Ended	6 Months Ended
	Mar. 19, 2013	Feb. 28, 2013 November 10, 2010 [Member]	Feb. 28, 2013 November 15, 2012 [Member]	Feb. 28, 2013 August 8, 2012 [Member]	Feb. 28, 2013 May 8, 2012 [Member]	Feb. 28, 2013 February 14, 2012 [Member	Feb. 28, 2013 November 10, 2011 [Member]	Feb. 28, 2013 August 11, 2011 [Member]	Feb. 28, 2013 May 9, 2011 [Member]	Feb. 28, 2013 February 9, 2011 [Member]
Dividends Per Share of Common Stock (in Dollars per share)		$ 0.31	$ 0.31	$ 0.31	$ 0.31	$ 0.27	$ 0.27	$ 0.27	$ 0.27	$ 0.23
Record Date		Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2011	Feb. 28, 2011
Total $ Amount	$ 13,500	$ 13,510	$ 13,746	$ 13,727	$ 13,893	$ 12,085	$ 12,181	$ 12,165	$ 12,374	$ 10,612
Payment Date		Mar. 19, 2013	Dec. 18, 2012	Sep. 18, 2012	Jun. 19, 2012	Mar. 20, 2012	Dec. 20, 2011	Sep. 20, 2011	Jun. 21, 2011	Mar. 15, 2011