Changes in Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Changes in equity
Balance	$ 4,169,234	$ 3,899,337	$ 4,102,289	$ 3,930,586
Net income	234,718	252,863	407,152	382,493
Other comprehensive income	15,122	30,843	24,673	32,688
COMPREHENSIVE INCOME	249,840	283,706	431,825	415,181
Issuance of capital stock	2,331	2,365	7,268	7,590
Reissuance of treasury stock - net	37	(82)	(5,868)	3,277
Other (primarily stock compensation)	(22)	258	14,988	4,270
Dividends on common Stock	8		(119,877)	(172,344)
Net capital activities by noncontrolling interests			(9,197)	(2,976)
Balance	4,421,428	4,185,584	4,421,428	4,185,584
Common Shareholders
Changes in equity
Balance	4,032,165	3,778,035	3,972,806	3,821,850
Net income	226,163	244,823	381,814	358,911
Other comprehensive income	15,122	30,843	24,673	32,688
COMPREHENSIVE INCOME	241,285	275,666	406,487	391,599
Issuance of capital stock	2,331	2,365	7,268	7,590
Reissuance of treasury stock - net	37	(82)	(5,868)	3,277
Other (primarily stock compensation)	(22)	258	14,988	4,270
Dividends on common Stock	8		(119,877)	(172,344)
Balance	4,275,804	4,056,242	4,275,804	4,056,242
Noncontrolling Interests
Changes in equity
Balance	137,069	121,302	129,483	108,736
Net income	8,555	8,040	25,338	23,582
COMPREHENSIVE INCOME	8,555	8,040	25,338	23,582
Net capital activities by noncontrolling interests			(9,197)	(2,976)
Balance	$ 145,624	$ 129,342	$ 145,624	$ 129,342