Debt (Senior Notes) (Narrative) (Details) (Senior Notes, USD $)	1 Months Ended
	Sep. 30, 2012	Apr. 30, 2013	Jan. 31, 2013
Debt Instrument [Line Items]
Debt, face value	$ 350,000,000	$ 350,000,000	$ 350,000,000
Debt, stated interest rate in percentage	3.75%	3.75%	3.75%
Proceeds from issuance of long-term debt	345,800,000
Debt discount	1,300,000	1,172,000	1,238,000
Debt issuance costs	$ 2,900,000
Debt redemption price as a percent of principal amount	100.00%
Treasury Rate
Debt Instrument [Line Items]
Discount rate, basis spread on Treasury Rate	50.00%