Fair Value Measurements Narrative (Details) (USD $)	12 Months Ended							12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] $250 Million Senior Notes [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] $250 Million Senior Notes [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] $400 Million Senior Notes [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] $400 Million Senior Notes [Member]	Aug. 25, 2010 Fair Value, Inputs, Level 2 [Member] Senior Notes [Member] $250 Million Senior Notes [Member]	Jun. 27, 2012 Fair Value, Inputs, Level 2 [Member] Senior Notes [Member] $400 Million Senior Notes [Member]	Dec. 31, 2012 Mutual Funds [Member] Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Sales of Mutual Funds								$ 11,800,000
Defined Benefit Plan, Assets Transferred from the Irrevocable Trust								8,400,000
Defined Benefit Plan, Transfers Between Measurement Levels	0							3,400,000
Debt Instrument, Face Amount						250,000,000	400,000,000
Debt Instrument, Fair Value Disclosure		$ 261,300,000	$ 271,600,000	$ 416,000,000	$ 442,000,000