Fair Value Measurements and Derivative Instruments (Details) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of investment securities	$ 625,000,000	$ 861,000,000
Subsidiary ILC total investments	343,000,000	282,000,000
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	359,790,000
Liabilities, Fair Value Disclosure	0
Money market funds / commercial paper		239,157,000
Equity securities		0
Commingled fixed income securities		0
Debt securities - U.S. and foreign governments, agencies and municipalities		93,175,000
Debt securities - corporate		0
Mortgage-back / asset-back securities		0
Interest rate swaps		0
Foreign exchange contracts		0
Total assets		332,332,000
Foreign exchange contracts		0
Total liabilities		0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	289,988,000
Liabilities, Fair Value Disclosure	(4,950,000)
Money market funds / commercial paper		300,702,000
Equity securities		22,097,000
Commingled fixed income securities		27,747,000
Debt securities - U.S. and foreign governments, agencies and municipalities		19,042,000
Debt securities - corporate		31,467,000
Mortgage-back / asset-back securities		134,262,000
Interest rate swaps		15,465,000
Foreign exchange contracts		4,230,000
Total assets		555,012,000
Foreign exchange contracts		(1,439,000)
Total liabilities		(1,439,000)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Liabilities, Fair Value Disclosure	0
Money market funds / commercial paper		0
Equity securities		0
Commingled fixed income securities		0
Debt securities - U.S. and foreign governments, agencies and municipalities		0
Debt securities - corporate		0
Mortgage-back / asset-back securities		0
Interest rate swaps		0
Foreign exchange contracts		0
Total assets		0
Foreign exchange contracts		0
Total liabilities		0
Total Level [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	649,778,000
Liabilities, Fair Value Disclosure	(4,950,000)
Money market funds / commercial paper		539,859,000
Equity securities		22,097,000
Commingled fixed income securities		27,747,000
Debt securities - U.S. and foreign governments, agencies and municipalities		112,217,000
Debt securities - corporate		31,467,000
Mortgage-back / asset-back securities		134,262,000
Interest rate swaps		15,465,000
Foreign exchange contracts		4,230,000
Total assets		887,344,000
Foreign exchange contracts		(1,439,000)
Total liabilities		(1,439,000)
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	(3,681,473,000)	(4,233,909,000)
Portion at Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	(3,783,459,000)	(4,364,176,000)
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	244,403,000
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	25,345,000
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Money Market Funds [Member] | Total Level [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	269,748,000
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	23,605,000
Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Equity Securities [Member] | Total Level [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	23,605,000
Fixed Income Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Fixed Income Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	28,660,000
Fixed Income Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Fixed Income Securities [Member] | Total Level [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	28,660,000
US Treasury and Government [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	115,387,000
US Treasury and Government [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	20,890,000
US Treasury and Government [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
US Treasury and Government [Member] | Total Level [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	136,277,000
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	34,834,000
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Corporate Debt Securities [Member] | Total Level [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	34,834,000
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	139,808,000
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Collateralized Mortgage Backed Securities [Member] | Total Level [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	139,808,000
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	11,036,000
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Interest Rate Swap [Member] | Total Level [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	11,036,000
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Liabilities, Fair Value Disclosure	0
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	5,810,000
Liabilities, Fair Value Disclosure	(4,950,000)
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Liabilities, Fair Value Disclosure	0
Foreign Exchange Contract [Member] | Total Level [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	5,810,000
Liabilities, Fair Value Disclosure	$ (4,950,000)