Supplemental Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Supplemental Information
Income taxes paid	$ 99,702	$ 124,521	$ 157,203
Interest paid	23,669	19,824	12,108
Comprehensive Income, Net of Tax, Attributable to Parent	385,716	322,617	450,298
Dividends declared but not paid at year end	$ 16,136	$ 16,671	$ 15,461