Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2013

Financial Instruments And Marketable Securities [Abstract]

Fair Value Hierarchy of Assets Measured on Recurring Basis

The following table presents the placement in the fair value hierarchy of assets that are measured at fair value on a recurring basis:

June 30, 2013:	Total		Level 1	Level 2	Level 3
Common stock	$	437	437	—	—
Total available-for-sale securities	$	437	437	—	—

December 31, 2012:	Total		Level 1	Level 2	Level 3
Common stock	$	354	354	—	—
Total available-for-sale securities	$	354	354	—	—

June 30, 2012:	Total		Level 1	Level 2	Level 3
Common stock	$	310	310	—	—
Government and agency securities	26,856		26,856	—	—
Total available-for-sale securities	$	27,166	27,166	—	—

Summary of Marketable Securities Treated as Available-for-Sale Securities

Marketable securities, all treated as available-for-sale securities, consist of the following:

June 30, 2013:	Amortized cost		Gross unrealized gains	Gross unrealized losses	Fair value
Common stock	$	197	240	—	437
Total available-for-sale securities	$	197	240	—	437

December 31, 2012:	Amortized cost		Gross unrealized gains	Gross unrealized losses	Fair value
Common stock	$	197	157	—	354
Total available-for-sale securities	$	197	157	—	354

June 30, 2012:	Amortized cost		Gross unrealized gains	Gross unrealized losses		Fair value
Common stock	$	197	113	—		310
Government and agency securities	26,862		—	(6	)	26,856
Total available-for-sale securities	$	27,059	113	(6	)	27,166

Summary of Future Maturities of Available-For-Sale Securities

Future maturities of our available-for-sale securities consist of the following:

	Less than 12 months			Greater than 12 months
June 30, 2013:	Amortized cost		Fair value	Amortized cost	Fair value
Common stock	$	197	437	—	—
Total available-for-sale securities	$	197	437	—	—