Common Stock Repurchase Program (Details) (USD $) In Millions, except Share data, unless otherwise specified	2 Months Ended	3 Months Ended	6 Months Ended
	Dec. 31, 2012	Mar. 31, 2013	Mar. 31, 2013
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount	$ 40.0
Treasury stock, shares acquired (shares)		103,000	248,000
Treasury stock, value, acquired, cost method		1.6	3.7
Treasury stock acquired, average cost (usd per share)		$ 16.00	$ 14.80
Stock repurchase program, remaining authorized repurchase amount			$ 36.3