Fair Value Measurements Narrative (Details) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014 Fair Value, Inputs, Level 2 [Member] $250 Million Senior Notes [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] $250 Million Senior Notes [Member]	Jun. 30, 2014 Fair Value, Inputs, Level 2 [Member] $400 Million Senior Notes [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] $400 Million Senior Notes [Member]
Fair Value Measurements [Line Items]
Defined benefit plan, transfers between measurement levels	$ 0	$ 0
Debt instrument fair value			$ 271,300,000	$ 261,300,000	$ 434,000,000	$ 416,000,000