Consolidated Statements of Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Capital in Excess of Par Value	Treasury Stock	Cumulative Net Income	Cumulative Dividends	Accumulated Other Comprehensive Income (Loss)	Other Equity	Noncontrolling Interests
Balances at beginning of period at Dec. 31, 2016	$ 15,281,472	$ 1,006,250	$ 363,071	$ 16,999,691	$ (54,741)	$ 4,803,575	$ (8,144,981)	$ (169,531)	$ 3,059	$ 475,079
Comprehensive income:
Net income (loss)	338,567					336,787				1,780
Other comprehensive income	(4,856)							(7,669)		2,813
Total comprehensive income	333,711
Increase in noncontrolling interests				932
Decrease in noncontrolling interests	(4,680)									(5,612)
Amounts related to stock incentive plans, net of forfeitures	(1,931)		336	6,903	(7,565)				(1,605)
Proceeds from issuance of common stock	118,984		1,780	117,204
Redemption of preferred stock	(287,509)	(287,500)		9,760		(9,769)
Option compensation expense	10								10
Cash dividends paid:
Common stock	(315,415)						(315,415)
Preferred Stock	(14,379)						(14,379)
Balances at end of period at Mar. 31, 2017	15,110,263	718,750	365,187	17,134,490	(62,306)	5,130,593	(8,474,775)	(177,200)	1,464	474,060
Balances at beginning of period at Dec. 31, 2017	14,925,452	718,503	372,449	17,662,681	(64,559)	5,316,580	(9,471,712)	(111,465)	670	502,305
Comprehensive income:
Net income (loss)	454,538					449,347				5,191
Other comprehensive income	16,326							20,212		(3,886)
Total comprehensive income	470,864
Decrease in noncontrolling interests	(15,876)			(13,157)						(2,719)
Amounts related to stock incentive plans, net of forfeitures	7,098		150	11,085	(4,137)				0
Proceeds from issuance of common stock	7,190		130	7,060
Conversion of preferred stock	0	(5)		5
Cash dividends paid:
Common stock	(323,726)						(323,726)
Preferred Stock	(11,676)						(11,676)
Balances at end of period at Mar. 31, 2018	$ 15,059,326	$ 718,498	$ 372,729	$ 17,667,674	$ (68,696)	$ 5,765,927	$ (9,807,114)	$ (91,253)	$ 670	$ 500,891