Financial Instruments (Contractual Maturities) (Details 3) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Financial Instruments Contractual Maturities Details 3
Due within one year, amortized cost	$ 69,674	$ 65,637
Due after one year through five years, amortized cost	1,422	17,629
Due after five years through ten years, amortized cost	0	0
Due after ten years, amortized cost	0	0
Due within one year, fair value	69,660	65,632
Due after one year through five years, fair value	1,423	17,612
Due after five years through ten years, fair value	0
Due after ten years, fair value	0
Total debt securities, amortized cost	71,096	83,266
Total debt securities, fair value	$ 71,083	$ 83,244