Restructuring Charges (Details) (USD $)	0 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 Severance	Dec. 31, 2012 Severance
Restructuring Charges
Restructuring liability expected to be paid	$ 500,000
Restructuring charges
Restructuring costs accrued and unpaid			700,000
Changes in restructuring liability
Balance at the beginning of the period		659,000
Severance and related costs		2,222,000
Cash payments		(2,392,000)
Balance at the end of the period		$ 489,000