CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) (USD $) In Thousands	Class A ordinary shares/ Common stock [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Treasury shares [Member]	Accumulated other comprehensive income (loss) [Member]	Total
Balance at Dec. 31, 2011	$ 15,947	$ 1,478,233	$ 3,186,362	$ (128,884)	$ (225,671)	$ 4,325,987
Balance (in shares) at Dec. 31, 2011	123,581
Net shares issued (acquired) under share-based compensation plans	1	(19,609)	0	17,294	0	(2,314)
Net shares issued (acquired) under share-based compensation plans (in shares)	561
Share-based compensation	0	4,672	0	0	0	4,672
Excess tax benefit from share-based compensation plans	0	276	0	0	0	276
Retirement benefit adjustments, net of taxes	0	0	0	0	3,389	3,389
Net income	0	0	49,517	0	0	49,517
Balance at Mar. 31, 2012	15,948	1,463,572	3,235,879	(111,590)	(222,282)	4,381,527
Balance (in shares) at Mar. 31, 2012	124,142
Balance at Dec. 31, 2012	15,593	1,372,135	3,366,964	(1,886)	(221,082)	4,531,724
Balance (in shares) at Dec. 31, 2012	124,211
Net shares issued (acquired) under share-based compensation plans	1	1,083	0	(4,112)	0	(3,028)
Net shares issued (acquired) under share-based compensation plans (in shares)	(43)
Share-based compensation	0	5,575	0	0	0	5,575
Excess tax benefit from share-based compensation plans	0	112	0	0	0	112
Retirement benefit adjustments, net of taxes	0	0	0	0	3,628	3,628
Net income	0	0	68,134	0	0	68,134
Balance at Mar. 31, 2013	$ 15,594	$ 1,378,905	$ 3,435,098	$ (5,998)	$ (217,454)	$ 4,606,145
Balance (in shares) at Mar. 31, 2013	124,168