Fair Value Measurements and Derivative Instruments (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2013 Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Total Level [Member]	Dec. 31, 2012 Total Level [Member]	Mar. 31, 2013 Carrying (Reported) Amount, Fair Value Disclosure [Member]	Dec. 31, 2012 Carrying (Reported) Amount, Fair Value Disclosure [Member]	Mar. 31, 2013 Portion at Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2012 Portion at Fair Value, Fair Value Disclosure [Member]	Mar. 31, 2013 Money Market Funds [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Money Market Funds [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Money Market Funds [Member] Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Money Market Funds [Member] Total Level [Member]	Mar. 31, 2013 Equity Securities [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Equity Securities [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Equity Securities [Member] Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Equity Securities [Member] Total Level [Member]	Mar. 31, 2013 Fixed Income Securities [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Fixed Income Securities [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Fixed Income Securities [Member] Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Fixed Income Securities [Member] Total Level [Member]	Mar. 31, 2013 US Treasury and Government [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 US Treasury and Government [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 US Treasury and Government [Member] Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 US Treasury and Government [Member] Total Level [Member]	Mar. 31, 2013 Corporate Debt Securities [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Corporate Debt Securities [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Corporate Debt Securities [Member] Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Corporate Debt Securities [Member] Total Level [Member]	Mar. 31, 2013 Collateralized Mortgage Backed Securities [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Collateralized Mortgage Backed Securities [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Collateralized Mortgage Backed Securities [Member] Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Collateralized Mortgage Backed Securities [Member] Total Level [Member]	Mar. 31, 2013 Interest Rate Swap [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Interest Rate Swap [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Interest Rate Swap [Member] Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Interest Rate Swap [Member] Total Level [Member]	Mar. 31, 2013 Foreign Exchange Contract [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Foreign Exchange Contract [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Foreign Exchange Contract [Member] Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Foreign Exchange Contract [Member] Total Level [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Document Period End Date	Mar. 31, 2013
Derivative Asset, Fair Value, Net	$ 1,000,000
Assets, Fair Value Disclosure		655,014,000		328,361,000		0		983,375,000						532,425,000	37,554,000	0	569,979,000	0	27,198,000	0	27,198,000	0	29,378,000	0	29,378,000	122,589,000	24,640,000	0	147,229,000	0	43,468,000	0	43,468,000	0	160,489,000	0	160,489,000	0	3,980,000	0	3,980,000	0	1,654,000	0	1,654,000
Liabilities, Fair Value Disclosure		0		(3,288,000)		0		(3,288,000)																																		0	(3,288,000)	0	(3,288,000)
Money market funds / commercial paper			581,648,000		34,369,000		0		616,017,000
Equity securities			0		25,106,000		0		25,106,000
Commingled fixed income securities			0		29,359,000		0		29,359,000
Debt securities - U.S. and foreign governments, agencies and municipalities			124,221,000		18,908,000		0		143,129,000
Debt securities - corporate			0		43,926,000		0		43,926,000
Mortgage-back / asset-back securities			0		162,375,000		0		162,375,000
Interest rate swaps			0		10,117,000		0		10,117,000
Foreign exchange contracts			0		2,582,000		0		2,582,000
Total assets			705,869,000		326,742,000		0		1,032,611,000
Foreign exchange contracts			0		(1,174,000)		0		(1,174,000)
Total liabilities			0		(1,174,000)		0		(1,174,000)
Long-term debt										$ (4,032,634,000)	$ (4,017,375,000)	$ (4,229,484,000)	$ (4,200,970,000)