Long-Term Debt (Narrative) (Details) (USD $)	9 Months Ended
	Sep. 30, 2014
Debt Instrument [Line Items]
Repayment of convertible notes	$ 187,000,000
Shares issued in conjunction with the conversion feature of the Notes	249,000
Stock received in written call transaction	266,000
Standby letters of credit issued	36,900,000
Unused lines of credit	238,300,000
2014 Credit Agreement [Member]
Debt Instrument [Line Items]
Debt instrument term	5 years
Deferred financing costs	900,000
2014 Credit Agreement [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate	1.13%
2014 Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Face amount of debt	350,000,000
2014 Credit Agreement [Member] | Medium-term Notes [Member]
Debt Instrument [Line Items]
Face amount of debt	$ 100,000,000