Property and Equipment (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Unfunded construction and equipment purchases	$ 7.7
Depreciation expense	$ 33.2	$ 29.8	$ 26.7
Building and Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life	20 years
Building and Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life	40 years
Movable Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life	3 years
Movable Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life	10 years