CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (USD $) In Thousands, unless otherwise specified	Total	COMMON STOCK (Note 7)	TREASURY STOCK (Note 7)	RETAINED EARNINGS	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	NONCONTROLLING INTERESTS	COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS
Balance at Dec. 31, 2010		$ 2,421,372	$ (2,239)	$ 1,423,961	$ (159,767)	$ 91,899
Increase (Decrease) in Shareholders' Equity
Issuance of common stock		22,875
Purchase of treasury stock			(3,720)
Reissuance of treasury stock used for stock compensation			1,242
Net income attributable to common shareholders	339,473			339,473			339,473
Common stock dividends declared ($2.23, $2.67, and $ 2.10 per share)				(228,951)
Net income attributable to noncontrolling interests	(27,467)					27,467
Net capital activities by noncontrolling interests						(10,630)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDER
Other comprehensive income attributable to common shareholders	7,605				7,604		7,605
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	347,078						347,078
Balance at Dec. 31, 2011	3,930,586	2,444,247	(4,717)	1,534,483	(152,163)	108,736
Increase (Decrease) in Shareholders' Equity
Issuance of common stock		22,676
Purchase of treasury stock			(4,607)
Reissuance of treasury stock used for stock compensation			5,113
Net income attributable to common shareholders	381,542			381,542			381,542
Common stock dividends declared ($2.23, $2.67, and $ 2.10 per share)				(291,923)
Net income attributable to noncontrolling interests	(31,622)					31,622
Net capital activities by noncontrolling interests						(10,875)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDER
Other comprehensive income attributable to common shareholders	38,155				38,155		38,155
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	419,697						419,697
Balance at Dec. 31, 2012	4,102,289	2,466,923	(4,211)	1,624,102	(114,008)	129,483
Increase (Decrease) in Shareholders' Equity
Issuance of common stock		24,635
Purchase of treasury stock			(9,727)
Reissuance of treasury stock used for stock compensation			9,630
Net income attributable to common shareholders	406,074			406,074			406,074
Common stock dividends declared ($2.23, $2.67, and $ 2.10 per share)				(244,903)
Net income attributable to noncontrolling interests	(33,892)					33,892
Net capital activities by noncontrolling interests						(17,385)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDER
Other comprehensive income attributable to common shareholders	35,955				35,955		35,955
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	442,029						442,029
Balance at Dec. 31, 2013	$ 4,340,460	$ 2,491,558	$ (4,308)	$ 1,785,273	$ (78,053)	$ 145,990