Computation of Earnings Per Ordinary Share and Ordinary Share Equivalent - Computation of basic and diluted earnings per share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic earnings per ordinary share and ordinary share equivalents:
Net income (loss) attributable to ordinary shareholders									$ 188,340	$ 1,059,916	$ 651,128
Weighted average ordinary shares outstanding									267,103	287,801	307,372
Basic earnings per ordinary share & ordinary share equivalents outstanding (in Dollars per share)	$ 0.54	$ 0.27	$ (1.03)	$ 0.93	$ 1.07	$ 0.48	$ 0.94	$ 1.19	$ 0.71	$ 3.68	$ 2.12
Diluted earnings per ordinary share and ordinary share equivalents:
Weighted average ordinary shares outstanding									267,103	287,801	307,372
Impact of share based compensation and certain conversion features									4,424	4,268	2,910
Weighted average ordinary shares outstanding - diluted									271,527	292,069	310,282
Diluted earnings per ordinary share & ordinary share equivalents outstanding (in Dollars per share)	$ 0.53	$ 0.27	$ (1.03)	$ 0.91	$ 1.05	$ 0.47	$ 0.93	$ 1.17	$ 0.69	$ 3.63	$ 2.10
Dividends per share paid on ordinary shares									$ 0.64	$ 0.56	$ 0.44