Convertible Senior Notes

In February 2014, the Company issued $690.0 million in par value of convertible senior notes due 2019 (the "Notes"). The Notes are senior unsecured obligations of the Company, do not bear regular interest and mature on February 15, 2019, unless repurchased or converted prior to maturity.

At their option, holders may convert their Notes prior to the close of business on the business day immediately preceding August 15, 2018, only under the following circumstances:

•

during any calendar quarter commencing after the calendar quarter ended June 30, 2014 (and only during such calendar quarter), if the last reported sale price of the Company's common stock for at least 20 trading days (whether or not consecutive) during the 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 on each applicable trading day; or


•	during the five business day period after any five consecutive trading day period in which the trading price per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company's common stock and the conversion rate on each such trading day; or upon the occurrence of specified corporate events.

On or after August 15, 2018, holders may convert all or any portion of their Notes at any time prior to the close of business on the second scheduled trading day immediately preceding the maturity date, regardless of the foregoing circumstances.

Upon conversion, the Company, at its election, may pay or deliver to holders cash, shares of the Company's common stock or a combination of cash and shares of the Company's common stock. The initial conversion rate is 11.1651 shares of the Company's common stock per $1,000 principal amount, which is equivalent to an initial conversion price of approximately $89.56 per share, subject to adjustments in certain events, and represents a potential conversion into 7.7 million shares.

In accounting for the issuance of the Notes, the Company separated the Notes into liability and equity components. The carrying cost of the liability component was calculated by measuring the fair value of a similar debt obligation that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the par value of the Notes. The difference between the principal amount of the Notes and the proceeds allocated to the liability component (“debt discount”) is amortized to interest expense using the effective interest method over the term of the Notes. The equity component is recorded in additional paid-in capital in the consolidated balance sheet and will not be remeasured as long as it continues to meet the conditions for equity classification.

In accounting for the transaction costs related to the issuance of the Notes, the Company allocated the total transaction costs incurred to the liability and equity components based on their relative values. Transaction costs attributable to the liability component are being amortized to interest expense over the term of the Notes, and transaction costs attributable to the equity component are netted against the equity component of the Notes in stockholders’ equity.

The Notes consist of the following components as of March 31, 2018 and December 31, 2017 (in thousands):



	March 31, 2018			December 31, 2017
Liability component:
Principal	$	690,000		$	690,000
Less: debt discount and issuance costs, net of amortization	(21,255		)	(27,087		)
Net carrying amount	$	668,745		$	662,913

Equity component:	$	101,276		$	101,276

The estimated fair value of the Notes at March 31, 2018 was $712.9 million. The fair value was determined based on the quoted price of the Notes in an inactive market on the last trading day of the reporting period and has been classified as Level 2 within the fair value hierarchy. Based on the closing price of the Company's common stock of $70.98 on March 31, 2018, the value of the Notes if converted to common stock was less than the principal amount of $690.0 million.

The Company used $62.0 million of the proceeds from the offering to repurchase shares of its common stock, concurrent with the issuance of the Notes. The repurchase was made in accordance with a share repurchase program previously approved by the Board of Directors. Additionally, $23.3 million of the proceeds was used for the net cost of convertible note hedge and warrant transactions. The remaining net proceeds are for working capital, share repurchases and other general corporate purposes, as well as for potential acquisitions and strategic transactions.

Note Hedge

To minimize the impact of potential dilution upon conversion of the Notes, the Company entered into convertible note hedge transactions with respect to its common stock in February 2014. The Company paid $101.3 million for the note hedge transactions. The note hedge transactions cover approximately 7.7 million shares of the Company’s common stock at a strike price that corresponds to the initial conversion price of the Notes, also subject to adjustment, and are exercisable upon conversion of the Notes. The note hedge transactions are intended to reduce dilution in the event of conversion of the Notes.

Warrants

Separately, in February 2014, the Company entered into warrant transactions, whereby the Company sold warrants to acquire, subject to anti-dilution adjustments, up to 7.7 million shares of the Company’s common stock at a strike price of approximately $104.49 per share. The Company received aggregate proceeds of $78.0 million from the sale of the warrants. The convertible note hedge and warrant transactions will generally have the effect of increasing the conversion price of the Notes to approximately $104.49 per share.

Interest Expense

The Notes do not bear regular interest, but have an effective interest rate of 3.2% attributable to the conversion feature. The following table sets forth total interest expense included in the consolidated statements of income related to the Notes for the three months ended March 31, 2018 and 2017 (in thousands):



	For the Three Months Ended March 31,
	2018			2017
Amortization of debt discount and issuance costs	$	5,832		$	5,632
Capitalization of interest expense	(982		)	(1,035		)
Total interest expense	$	4,850		$	4,597