Supplemental Information (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Supplemental Information
Income taxes paid	$ 31,366	$ 34,949	$ 88,973	$ 101,164
Interest paid	785	151	12,937	9,714
Cash paid for commutation	4,210	0	37,849	0
Comprehensive Income, Net of Tax, Attributable to Parent	$ 116,568	$ 154,317	$ 281,737	$ 337,068