Derivatives And Fair Value Measurements Derivatives, Investments And Fair Value Measurements (Held-to-maturity securities) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013
Fixed Income Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	$ 29,419,000
Held-to-maturity Securities, Unrecognized Holding Gain	0
Held-to-maturity Securities, Unrecognized Holding Loss	(22,000)
Held-to-maturity Securities, Fair Value	29,397,000
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	136,924,000
Held-to-maturity Securities, Unrecognized Holding Gain	27,000
Held-to-maturity Securities, Unrecognized Holding Loss	(25,000)
Held-to-maturity Securities, Fair Value	136,926,000
Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	166,343,000
Held-to-maturity Securities, Unrecognized Holding Gain	27,000
Held-to-maturity Securities, Unrecognized Holding Loss	(47,000)
Held-to-maturity Securities, Fair Value	$ 166,323,000