Fair Value Measurements (Narrative) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Statement [Line Items]
Restricted marketable securities	$ 3,500,000
Fixed Interest Rate [Member]
Statement [Line Items]
Long-term debt, carrying value	1,378,700,000
Long-term debt, fair value	1,362,000,000
Variable Interest Rate [Member]
Statement [Line Items]
Long-term debt, fair value	870,000,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Statement [Line Items]
Supplemental executive retirement savings plan investments - Level 2	$ 16,800,000	$ 13,300,000