Short-Term Investments

3 Months Ended

Mar. 31, 2015

Investments Debt And Equity Securities [Abstract]

Short-Term Investments

3. Short-Term Investments

The Company invests its excess cash in investment securities, principally debt instruments of financial institutions and corporations with strong credit ratings. The following represents a summary of the estimated fair value of short-term investments at March 31, 2015 and December 31, 2014 (in thousands):

At March 31, 2015	Maturity (in years)	Amortized Cost		Unrealized Gain		Unrealized Loss		Estimated Fair Value
Available-for-sale investment securities:
Commercial paper	Less than 1	$	45,156	$	38	$	—	$	45,194
Government-sponsored enterprise securities	Less than 1		8,501		1		—		8,502
		$	53,657	$	39	$	—	$	53,696
Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants		$	134	$	4	$	—	$	138
Total		$	53,791	$	43	$	—	$	53,834

At December 31, 2014	Maturity (in years)	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Available-for-sale investment securities:
Commercial paper	Less than 1	$	32,536	$	9	$	—		$	32,545
Government-sponsored enterprise securities	Less than 1		3,504		—		(1	)		3,503
		$	36,040	$	9	$	(1	)	$	36,048
Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants		$	56	$	2	$	—		$	58
Total		$	36,096	$	11	$	(1	)	$	36,106