Shareholders' Equity (Narrative) (Details) (USD $) In Millions	1 Months Ended			6 Months Ended
	Aug. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Jul. 31, 2011
Shareholders' Equity
Share repurchase authorized amount	$ 100.0	$ 100.0	$ 100.0	$ 200.0
Shares repurchased during the period				$ 200.0