Fair Value Measurements (Details) (Recurring basis, USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value
Assets (Liabilities) at fair value
Nonqualified deferred compensation assets	$ 3,819	$ 3,653
Nonqualified deferred compensation liability	(3,819)	(3,653)
Designated derivatives assets	2,458
Non-designated derivatives assets		839
Non-designated derivatives liabilities		(336)
Contingent consideration for acquisition of business	(47,060)	(71,460)
Level 1
Assets (Liabilities) at fair value
Nonqualified deferred compensation assets	3,819	3,653
Nonqualified deferred compensation liability	(3,819)	(3,653)
Level 2
Assets (Liabilities) at fair value
Designated derivatives assets	2,458
Non-designated derivatives assets		839
Non-designated derivatives liabilities		(336)
Level 3
Assets (Liabilities) at fair value
Contingent consideration for acquisition of business	$ (47,060)	$ (71,460)