Fair Value Measurements (Details) (Commitments and contingencies, USD $)	3 Months Ended
	Jun. 30, 2012	Mar. 31, 2012
Commitments and contingencies
Reconciliation of liability measured at fair value
Balance at the beginning of the period	$ 2,204,000
Change in fair value included in net income	(334,000)
Balance at the end of the period	1,870,000
Fair value disclosure of liabilities
Current portions of contingent consideration included within accrued liabilities	$ 1,900,000	$ 1,600,000