Equity (Details) (USD $)	12 Months Ended			146 Months Ended	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Mar. 31, 2015
Treasury Stock, Shares, Acquired				37,867,189
Treasury Stock, Value, Acquired, Cost Method				$ 1,500,000,000
Accumulated Other Comprehensive Income (Loss), Net of Tax	(11,894,000)	(8,626,000)		(11,894,000)
Treasury Stock Acquired, Average Cost Per Share				$ 38.43
Treasury Stock, Shares, Retired	1,150,000			30,975,406
Treasury Stock, Retired, Cost Method, Amount	0	0	0	840,000,000
Treasury Stock, Shares	1,963,018	1,648,613		1,963,018
Treasury shares, Remaining shares authorized to be purchased	2,596,982			2,596,982
Common Stock, Dividends, Per Share, Cash Paid	$ 0.50
Dividends	(89,089,000)	(58,642,000)	(52,950,000)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	718,000	(55,000)		718,000
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Transition Assets (Obligations), before Tax	65,000	131,000		65,000
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	(11,595,000)	(8,702,000)		(11,595,000)
Subsequent Event [Member]
Treasury Stock, Shares, Acquired					315,287
Treasury Stock, Value, Acquired, Cost Method					$ 33,800,000
Common Stock, Dividends, Per Share, Declared					$ 0.55