Restructuring Charges (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended						12 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Severance	Dec. 31, 2012 Severance	Dec. 31, 2010 Severance
Changes in restructuring liability
Balance at the beginning of the period									$ 659	$ 171	$ 171
Severance and related costs	400	1,800	600	600	100	2,900	2,334	4,169	2,334	4,169
Cash payments									(2,950)	(3,551)
Non-cash items										(130)
Balance at the end of the period									$ 43	$ 659	$ 171