Fair Value Measurements (Details) (Recurring basis, USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Fair Value
Assets (Liabilities) assets at fair value
Nonqualified deferred compensation assets	$ 3,415	$ 1,991
Nonqualified deferred compensation liability	(3,415)	(1,991)
Designated derivatives assets	1,482	1,117
Designated derivatives liabilities	(544)	(87)
Contingent, consideration for acquisition of business	(67,900)	(91,600)
Level 1
Assets (Liabilities) assets at fair value
Nonqualified deferred compensation assets	3,415	1,991
Nonqualified deferred compensation liability	(3,415)	(1,991)
Level 2
Assets (Liabilities) assets at fair value
Designated derivatives assets	1,482	1,117
Designated derivatives liabilities	(544)	(87)
Level 3
Assets (Liabilities) assets at fair value
Contingent, consideration for acquisition of business	$ (67,900)	$ (91,600)