9. Debt

The components of the convertible notes are as follows (in thousands):


				Carrying Amount,
	Interest Rates			March 31,		December 31,
Debt	March 31, 2016		Maturities	2016		2015
0.375% Convertible Senior Notes due 2018	0.375	%	2018	$	328,173		324,031
1.25% Convertible Senior Notes due 2020	1.25	%	2020		299,469		295,862
					627,642		619,893
Less current portion					—		—
				$	627,642	$	619,893

The carrying amount and fair value of our convertible notes are as follows (in thousands):


	March 31, 2016				December 31, 2015
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
0.375% Convertible Senior Notes due 2018		328,173		574,922		324,031		807,422
1.25% Convertible Senior Notes due 2020		299,469		588,427		295,862		816,123
	$	627,642	$	1,163,349	$	619,893	$	1,623,545

The fair values of the 0.375% Convertible Senior Notes due 2018 (the “2018 Notes”) and the 1.25% Convertible Senior Notes due 2020 (the “2020 Notes”) are based on data from readily available pricing sources which utilize market observable inputs and other characteristics for similar types of instruments, and, therefore, these convertible senior notes are classified within Level 2 in the fair value hierarchy.

Prior to May 14, 2014, the 2018 and 2020 Notes were not convertible except in connection with a make whole fundamental change, as defined in the respective indentures. Beginning on, and including, May 15, 2014, the 2018 and 2020 Notes are convertible prior to the close of business on the business day immediately preceding May 15, 2018, in the case of the 2018 Notes, and May 15, 2020, in the case of the 2020 Notes, only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on March 31, 2014 (and only during such calendar quarter), if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price for the 2018 Notes or 2020 Notes, as applicable, on each applicable trading day; (2) during the five business day period after any five consecutive trading day period (the “measurement period”) in which the trading price per $1,000 principal amount of 2018 Notes or 2020 Notes, as applicable, for each trading day of the measurement period was less than 98% of the product of the last reported sale price of our common stock and the conversion rate for the 2018 Notes or 2020 Notes, as applicable, on each such trading day; or (3) upon the occurrence of specified corporate events. On or after May 15, 2018, in the case of the 2018 Notes, and May 15, 2020, in the case of the 2020 Notes, until the close of business on the second scheduled trading day immediately preceding the relevant maturity date, the Notes are convertible at any time, regardless of the foregoing circumstances. Upon conversion we will pay or deliver, as the case may be, cash, shares of common stock or a combination of cash and shares of common stock, at our election.

On April 1, 2016, the 2018 Notes and 2020 Notes became convertible through at least June 30, 2016, based on meeting the conversion criteria related to the sale price of our common stock during the calendar quarter ended March 31, 2016 as described in (1) above. Management’s intent is to settle any conversions of 2018 Notes or 2020 Notes during this period in shares of our common stock and, therefore, the 2018 Notes and 2020 Notes are reflected in long term liabilities on the condensed consolidated balance sheet at March 31, 2016.