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, 2014		$ 87,237	$ 34,150	$ 3,949,665	$ (34,083)	$ (7,915)	$ (29,576)	$ 3,408	$ 6,270,811	$ (3,258,870)
Net income	$ 248,099								248,099
Net income attributable to noncontrolling interests	(2,182)								(2,182)
Reissuance of common shares									(26,917)	29,227
Dividends on common shares									(33,185)
Dividends on preferred shares	(14,184)								(14,184)
Stock compensation expense, net of taxes paid				9,800
Cancellation Of Treasury Shares		0		0					0	0
Cancellation of common shares		0		0
Settlement of share-based awards upon change in control	0			0
Change in currency translation adjustment						(5,063)
Change in net unrealized gain on designated net investment hedges						2,559
Change in unfunded pension obligation, net of tax	(436)						(436)
Change in unrealized losses on investments, net of tax	(217)							(217)
Repurchase of common shares										(59,266)
Balance at end of period at Mar. 31, 2015	7,197,145	87,237	34,150	3,959,465	(37,240)	(10,419)	(30,012)	3,191	6,442,442	(3,288,909)
Noncontrolling interests											$ 57,683
Total shareholders' equity	7,254,828
Noncontrolling interests	2,450
Total shareholders' equity	6,902,951
Balance at beginning of period at Dec. 31, 2015	6,900,501	87,237	34,150	3,982,147	(83,283)	(53,970)	(31,861)	2,548	6,146,802	(3,266,552)
Net income	215,626								215,626
Net income attributable to noncontrolling interests	0								0
Reissuance of common shares									(17,229)	18,390
Dividends on common shares									(186,430)
Dividends on preferred shares	(14,184)								(14,184)
Stock compensation expense, net of taxes paid				48,731
Cancellation Of Treasury Shares		(39,082)		(1,466,363)					(1,742,717)	(3,248,162)
Cancellation of common shares		(48,155)		(48,155)
Settlement of share-based awards upon change in control	75,311			(75,311)
Change in currency translation adjustment						10,760
Change in net unrealized gain on designated net investment hedges						10,363
Change in unfunded pension obligation, net of tax	(829)						(829)
Change in unrealized losses on investments, net of tax	(203)							(203)
Repurchase of common shares										0
Balance at end of period at Mar. 31, 2016	6,910,185	$ 0	$ 34,150	$ 2,537,359	$ (63,192)	$ (32,847)	$ (32,690)	$ 2,345	$ 4,401,868	$ 0
Noncontrolling interests	0										$ 0
Total shareholders' equity	$ 6,910,185