Restructuring Charges (Details) (USD $)			6 Months Ended	18 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Severance and Benefits	Jun. 30, 2013 Severance and Benefits
Restructuring Charges
Total recognized cost				$ 6,700,000
Total restructuring charges expected upon completion			7,000,000
Changes in the restructuring accrual
Balance of restructuring accrual at the beginning of the period			3,142,000
Restructuring charges			3,116,000
Cash payments			(4,682,000)
Balance of restructuring accrual at the end of the period			1,576,000	1,576,000
Restructuring accrual included in accrued liabilities	$ 40,159,000	$ 37,096,000	$ 1,600,000	$ 1,600,000