Operating Leases (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Leases [Abstract]
Rental expense for all non-cancelable operating leases	$ 18,600,000	$ 18,600,000	$ 18,400,000
Future minimum rentals under operating leases:
Future minimum operating lease payments due, 2013	16,624,000
Future minimum operating lease payments due, 2014	13,285,000
Future minimum operating lease payments due, 2015	9,450,000
Future minimum operating lease payments due, 2016	8,212,000
Future minimum operating lease payments due, 2017	8,168,000
Future minimum operating lease payments due, 2018 and thereafter	$ 40,757,000