Long-Term Debt Long Term Debt (Details textual) (USD $) In Millions, unless otherwise specified	1 Months Ended
	Aug. 31, 2011 Three Point Seven Five Percent Senior Unsecured Notes Due September First, Twenty Sixteen [Member]	Apr. 30, 2013 Term loan facility [Member]	Apr. 05, 2013 Term loan facility [Member]
Debt Instrument [Line Items]
Senior unsecured notes, issued amount	$ 250		$ 150
Senior unsecured notes, interest rate	3.75%
Senior unsecured notes, maturity date	Sep. 01, 2016	Apr. 05, 2019
Senior unsecured notes, proceeds	$ 247.7
Senior unsecured notes, term (in years)	5 years
Senior unsecured notes, interest payments	semiannually
Senior unsecured notes, interest payment dates	March 1 and September 1