4. Held-to-maturity Investments

The Company invests its excess cash balances in short-term and long-term fixed-income investments. The Company determines the appropriate classification of investments at the time of purchase and re-evaluates such designation as of each balance sheet date. Debt securities carried at amortized cost are classified as held-to-maturity when the Company has the positive intent and ability to hold the securities to maturity.

The following tables provide information relating to held-to-maturity investments:

 

		Amortized Cost				Gross  Unrealized Gains				Gross  Unrealized Losses				Fair  Value
At December 31, 2015:
Held-to-maturity investments
U.S. Government treasury		$	38,551			$	—			$	(47	)		$	38,504
Total held-to-maturity investments		$	38,551			$	—			$	(47	)		$	38,504

 

		Amortized Cost				Gross  Unrealized Gains				Gross  Unrealized Losses				Fair  Value
At December 31, 2014:
Held-to-maturity investments
U.S. Government treasury and agency securities		$	72,556			$	2			$	(26	)		$	72,532
Total held-to-maturity investments		$	72,556			$	2			$	(26	)		$	72,532

The amortized cost and fair value of held-to-maturity investments by contractual maturities at December 31, 2015, are as follows:

 

		Held-to-Maturity
		Amortized Cost				Fair  Value
Maturing in one year or less		$	38,551			$	38,504
Total		$	38,551			$	38,504