CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY AND REDEEMABLE NONCONTROLLING INTERESTS - USD ($) $ in Millions	Redeemable Non-Controlling Interests	Convertible Preference Shares	Common Shares	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Shares	Non-Controlling Interests	Total
Balance at Dec. 31, 2013		$ 690	$ 1	$ 4,967	$ 6,891	$ (2,572)	$ (120)	$ 231	$ 10,088
Balance at Dec. 31, 2013	$ 37
Balance (in shares) at Dec. 31, 2013		6,900,000	147,796,784
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(9)
Net income (loss)					515			2	517
Accretion of noncontrolling interests	14			(14)					(14)
Other comprehensive income (loss)	(5)					(1,486)		(8)	(1,494)
Dividends on common shares					(192)				(192)
Dividends on preference shares					(34)				(34)
Dividends to noncontrolling interests on subsidiary common stock								(10)	(10)
Acquisition of Noncontrolling interest				(23)				29	6
Share-based compensation expense				49					49
Repurchase of common shares							(300)		(300)
Repurchase of common shares (in shares)			(3,780,987)
Issuance of common shares				74					74
Issuance of common shares (in shares)			1,687,401
Balance at Dec. 31, 2014		$ 690	$ 1	5,053	7,180	(4,058)	(420)	244	8,690
Balance at Dec. 31, 2014	37
Balance (in shares) at Dec. 31, 2014		6,900,000	145,703,198
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(14)
Net income (loss)					791			(1)	790
Accretion of noncontrolling interests	19			(19)					(19)
Other comprehensive income (loss)	(5)					(2,302)		(4)	(2,306)
Dividends on common shares					(212)				(212)
Dividends on preference shares					(34)				(34)
Dividends to noncontrolling interests on subsidiary common stock								(9)	(9)
Return of capital to noncontrolling interest								(19)	(19)
Share-based compensation expense				46					46
Repurchase of common shares							(300)		(300)
Repurchase of common shares (in shares)			(3,871,810)
Issuance of common shares				25					25
Issuance of common shares (in shares)			652,079
Balance at Dec. 31, 2015		$ 690	$ 1	5,105	7,725	(6,360)	(720)	211	6,652
Balance at Dec. 31, 2015	37								37
Balance (in shares) at Dec. 31, 2015		6,900,000	142,483,467
Increase (Decrease) in Stockholders' Equity
Net income (loss)	1
Net income (loss)					745			22	767
Accretion of noncontrolling interests	2			(2)					(2)
Other comprehensive income (loss)	(1)					382		4	386
Dividends on common shares					(228)				(228)
Dividends on preference shares					(34)				(34)
Dividends to noncontrolling interests on subsidiary common stock								(25)	(25)
Noncontrolling decrease from redemption								(6)	(6)
Acquisition of Noncontrolling interest	$ (39)			(2)				19	17
Deconsolidation of a subsidiary								(26)	(26)
Share-based compensation expense				44					44
Repurchase of common shares							(200)		(200)
Repurchase of common shares (in shares)			(3,296,230)
Issuance of common shares				(2)					(2)
Issuance of common shares (in shares)			313,625
Balance at Dec. 31, 2016		$ 690	$ 1	$ 5,143	$ 8,208	$ (5,978)	$ (920)	$ 199	$ 7,343
Balance (in shares) at Dec. 31, 2016		6,900,000	139,500,862