Financial Instruments (Contractual Maturities) (Details 3) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Financial Instruments Contractual Maturities Details 3
Due within one year, amortized cost	$ 94,236	$ 65,637
Due after one year through five years, amortized cost	16,195	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	94,179	65,632
Due after one year through five years, fair value	16,155	17,612
Due after five years through ten years, fair value	0
Due after ten years, fair value	0
Total debt securities, amortized cost	110,431	83,266
Total debt securities, fair value	$ 110,334	$ 83,244