Pension Plan (Details) - Change in unrecognized pension costs recorded in other comprehensive loss (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Change in unrecognized pension costs recorded in other comprehensive loss [Abstract]
Balance at beginning of year	$ 4,886	$ 6,361
Net actuarial loss (gain)	2,921	(952)
Recognized loss	(358)	(523)
Balance at end of year	$ 7,449	$ 4,886