Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Shares [Member]	Preferred shares	Additional Paid-in Capital [Member]	Accumulated other comprehensive loss [Member]	Foreign Currency translation adjustment [Member]	Unfunded pension obligation [Member]	Unrealized gain on investment [Member]	Retained Earnings [Member]	Common shares held in treasury [Member]	Noncontrolling Interest [Member]
Balance at beginning of period at Dec. 31, 2013		$ 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		17,524
Stock compensation expense, net of taxes paid				17,245
Change in foreign currency translation adjustment						3,209
Change in net unrealized gain on designated net investment hedges						0
Change in unfunded pension obligation, net of tax	$ 979						979
Change in unrealized losses on investments, net of tax	(668)							(668)
Net (loss) income	787,996								787,996
Net income attributable to noncontrolling interests	(9,914)								(9,914)
Reissuance of common shares									0	0
Dividends on common shares									(101,453)
Dividends on preferred shares	(42,551)								(42,551)
Repurchase of common shares										(368,404)
Balance at end of period at Sep. 30, 2014	7,013,980	87,142	34,150	3,936,396	(8,718)	4,186	(16,530)	3,626	6,040,875	(3,075,865)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling interests											$ 52,276
Total shareholders' equity	7,066,256
Noncontrolling interests	55,501
Total shareholders' equity	7,104,411
Balance at beginning of period at Dec. 31, 2014	7,048,910	87,237	34,150	3,949,665	(34,083)	(7,915)	(29,576)	3,408	6,270,811	(3,258,870)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares		0		0
Stock compensation expense, net of taxes paid				22,309
Change in foreign currency translation adjustment						(36,298)
Change in net unrealized gain on designated net investment hedges						2,362
Change in unfunded pension obligation, net of tax	(164)						(164)
Change in unrealized losses on investments, net of tax	(644)							(644)
Net (loss) income	(69,599)								(69,599)
Net income attributable to noncontrolling interests	(2,531)								(2,531)
Reissuance of common shares									(36,190)	48,953
Dividends on common shares									(100,154)
Dividends on preferred shares	(42,551)								(42,551)
Repurchase of common shares										(59,266)
Balance at end of period at Sep. 30, 2015	6,775,137	$ 87,237	$ 34,150	$ 3,971,974	$ (68,827)	$ (41,851)	$ (29,740)	$ 2,764	$ 6,019,786	$ (3,269,183)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling interests	2,212										$ 2,212
Total shareholders' equity	$ 6,777,349