Financing and Other Activities (Narrative) (Details) (USD $)	3 Months Ended	9 Months Ended
	Mar. 31, 2013	Sep. 30, 2013	Sep. 30, 2012
Repurchase Of Collateral Finance Facility Notes [Abstract]
Debt Instrument Repurchased Face Amount	$ 160,000,000
Repayments of Long-term Debt	112,000,000
Gains Losses On Extinguishment Of Collateral Finance Securities	46,500,000
Payments to Acquire Businesses, Net of Cash Acquired		12,500,000
Noncash or Part Noncash Acquisition, Value of Assets Acquired		147,300,000
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed		134,800,000
Debt Instrument, Issuance Date		Sep. 19, 2013
Debt Instrument, Interest Rate, Stated Percentage		4.70%
Debt Instrument, Maturity Date		Sep. 15, 2023
Debt Instrument, Face Amount		400,000,000
Proceeds from Issuance of Long-term Debt and Capital Securities, Net		395,100,000
Payments of Debt Issuance Costs		$ 3,400,000	$ 6,255,000