Share Capital (Details) - Authorized and issued	1 Months Ended	12 Months Ended					12 Months Ended					0 Months Ended			3 Months Ended	0 Months Ended		12 Months Ended			0 Months Ended		12 Months Ended
	Aug. 31, 2011 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2012 EUR (€)	Dec. 31, 2011 USD ($)	Aug. 31, 2008 USD ($)	Aug. 31, 2011 8.25% senior notes USD ($)	Dec. 31, 2010 November 2010 share repurchase plan USD ($)	Dec. 31, 2012 February 2012 share repurchase plan USD ($)	Dec. 31, 2012 Ordinary Shares USD ($)	Dec. 31, 2012 Undesignated shares USD ($)	Dec. 31, 2012 Subscriber shares EUR (€)	Aug. 15, 2011 Series C preference ordinary shares USD ($)	Feb. 16, 2011 Series C preference ordinary shares USD ($)	Feb. 12, 2010 Series C preference ordinary shares USD ($)	Dec. 31, 2011 Series C preference ordinary shares USD ($)	Dec. 05, 2011 Series D preference ordinary shares USD ($)	Oct. 15, 2011 Series D preference ordinary shares USD ($)	Dec. 31, 2012 Series D preference ordinary shares USD ($)	Dec. 31, 2011 Series D preference ordinary shares USD ($)	Dec. 31, 2010 Series D preference ordinary shares USD ($)	Feb. 16, 2011 Series E preference ordinary shares USD ($)	Mar. 15, 2007 Series E preference ordinary shares USD ($)	Dec. 31, 2012 Series E preference ordinary shares USD ($)
Shareholders Equity Disclosure [Line Items]
Authorized share capital, value		$ 9,999,900	€ 40,000
Ordinary shares, shares authorized (in shares)		999,990,000	999,990,000	999,990,000					500,000,000	499,990,000	40,000
Ordinary shares, par value (in dollars per share)		$ 0.01		$ 0.01					$ 0.01	$ 0.01	€ 1.00
Rollforward of ordinary shares issued and outstanding:
Balance at beginning of year, shares		315,645,796	315,645,796	316,396,000
Exercise of options, shares		383,000	383,000	72,000
Net issuance of restricted shares, shares		959,000	959,000	413,000
Share buybacks, shares		(18,306,000)	(18,306,000)	(31,692,000)								(2,811,000)	(30,000)	(4,400,000)							(500)
Issue of shares, shares	30,456,600	0	0	30,457,000
Balance at end of year, shares		298,681,573	298,681,573	315,645,796
Ordinary share buybacks:
Share repurchase authorization							190,000,000	750,000,000
Shares purchased and canceled during the period		18,306,000	18,306,000	31,692,000								2,811,000	30,000	4,400,000							500
Value of shares purchased and canceled during the period								401,600,000
Amount remaining under share repurchase plan								348,400,000
Equity Security Units:
Rate of interest of equity security units	10.75%
Senior notes, stated interest rate						8.25%
Face value of senior notes acquired and retired						575,000,000
Equity security unit exchange ratio, in shares	1.3242
Price per share on forward contract	$ 25.00				$ 25.00
Issue of shares, shares	30,456,600	0	0	30,457,000
Preferred shares and non-controlling interest in equity of consolidated subsidiaries:
Shares purchased and canceled during the period		18,306,000	18,306,000	31,692,000								2,811,000	30,000	4,400,000							500
Liquidation value of preferred shares repurchased													750,000	110,800,000		5,000,000					500,000
Liquidation preference per share												$ 25.00										$ 1,000
Price of preferred stock repurchased												71,000,000	650,000	94,200,000	900,000	3,700,000		0	3,650,000	0	470,000
Gain on repurchase of preferred stock														16,600,000		1,300,000
Value of shares issuable for consideration of cash and liquid investments																	350,000,000
Dividend rate, spread on LIBOR																	0.0312
Face value of notes repaid																	600,000,000
Stock repurchased and held																5,000
Preferred shares, shares issued																						1,000,000
Preferred shares, par value																						$ 0.01
Proceeds on issuance of preferred shares																						983,800,000
Reduction in non controlling interest due to share repurchase																					$ 130,000
Preferred shares, stated dividend per share																							$ 32.50
Maximum individual voting power as restricted by Articles of Assocation, percentage		10.00%	10.00%