Supplemental Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplemental Information
Income taxes paid	$ 107,918	$ 99,702	$ 124,521
Interest paid	24,107	23,669	19,824
Dividends declared but not paid at year end	16,680	16,136	16,671
Treasury stock payable	$ 5,657	$ 16	$ 0