Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair value of the Company's investments by type
Amortized Cost	$ 9,324	$ 15,775
Accrued Interest	28	57
Gross Unrealized Gains	6	27
Gross Unrealized Losses
Estimated Fair Value	9,358	15,859
Level 2 [Member] | U.S. Treasury securities [Member]
Fair value of the Company's investments by type
Amortized Cost		999
Accrued Interest		2
Gross Unrealized Gains		2
Gross Unrealized Losses
Estimated Fair Value		1,003
Level 2 [Member] | Obligations of U.S. Government and its agencies [Member]
Fair value of the Company's investments by type
Amortized Cost	3,501	3,505
Accrued Interest	6	6
Gross Unrealized Gains	1	2
Gross Unrealized Losses
Estimated Fair Value	3,508	3,513
Level 2 [Member] | Corporate debt securities [Member]
Fair value of the Company's investments by type
Amortized Cost	1,776	4,035
Accrued Interest	2	22
Gross Unrealized Gains	1	6
Gross Unrealized Losses
Estimated Fair Value	1,779	4,063
Level 2 [Member] | Commercial paper [Member]
Fair value of the Company's investments by type
Amortized Cost	797	1,695
Accrued Interest
Gross Unrealized Gains	1	1
Gross Unrealized Losses
Estimated Fair Value	798	1,696
Level 2 [Member] | Municipal obligations [Member]
Fair value of the Company's investments by type
Amortized Cost	3,250	5,541
Accrued Interest	20	27
Gross Unrealized Gains	3	16
Gross Unrealized Losses
Estimated Fair Value	$ 3,273	$ 5,584