Intangible Assets Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Intangible Assets [Abstract]
Intangible assets accumulated amortization	$ 19,871		$ 19,263
Amortization of Intangible Assets	$ 558	$ 0	$ 600	$ 0