Condensed Consolidated Statements of Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Parent [Member]	Common Shares [Member]	Preferred shares	Additional Paid-in Capital [Member]	Accumulated other comprehensive loss [Member]	Currency translation adjustment [Member]	Unfunded pension obligation [Member]	Unrealized gain (loss) on investment [Member]	Retained Earnings [Member]	Common shares held in treasury [Member]	Noncontrolling Interest [Member]
Total shareholders' equity at Dec. 31, 2012			$ 85,460	$ 35,750	$ 3,861,844	$ 10,597	$ 32,755	$ (27,370)	$ 5,212	$ 4,952,002	$ (2,012,157)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares			966		56,568
Issuance of preferred shares				10,000	231,265
Redemption of preferred shares				(11,600)	(269,265)
Change in currency translation adjustment	(16,912)						(16,912)
Change in unfunded pension obligation, net of tax	980							980
Change in unrealized losses on investments, net of tax	(692)								(692)
Net income	397,517									397,517
Net income attributable to noncontrolling interests	(5,296)									(5,296)
Dividends on common shares										(108,191)
Dividends on preferred shares	(43,678)									(43,678)
Loss on redemption of preferred shares	(9,135)									(9,135)
Repurchase of common shares											(594,336)
Total shareholders' equity at Sep. 30, 2013	6,624,176	6,571,687	86,426	34,150	3,880,412	(6,027)	15,843	(26,390)	4,520	5,183,219	(2,606,493)	52,489
Total shareholders' equity at Dec. 31, 2013	6,766,159		86,657	34,150	3,901,627	(12,238)	977	(17,509)	4,294	5,406,797	(2,707,461)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares			485		34,769
Issuance of preferred shares				0	0
Redemption of preferred shares				0	0
Change in currency translation adjustment	3,209						3,209
Change in unfunded pension obligation, net of tax	979							979
Change in unrealized losses on investments, net of tax	(668)								(668)
Net income	787,996									787,996
Net income attributable to noncontrolling interests	(9,914)									(9,914)
Dividends on common shares										(101,453)
Dividends on preferred shares	(42,551)									(42,551)
Loss on redemption of preferred shares	0									0
Repurchase of common shares											(368,404)
Total shareholders' equity at Sep. 30, 2014	$ 7,066,256	$ 7,013,980	$ 87,142	$ 34,150	$ 3,936,396	$ (8,718)	$ 4,186	$ (16,530)	$ 3,626	$ 6,040,875	$ (3,075,865)	$ 52,276