Treasury Stock	3 Months Ended
Mar. 31, 2019
Equity [Abstract]
TREASURY STOCK	TREASURY STOCK Stock Repurchase Program The Company’s Board of Directors authorized an ongoing stock repurchase program, of which $750.0 million was approved in October 2018. The Company may use the approved dollar authority to repurchase stock at any time until the approved amount is exhausted. The objective of the Company’s stock repurchase program is to improve stockholders’ returns. At March 31, 2019, approximately $674.1 million was available to repurchase common stock pursuant to the stock repurchase program. All shares repurchased are recorded as treasury stock. A portion of the funds used to repurchase stock over the course of the program was provided by net proceeds from the Convertible Notes and 2027 Notes offerings, as well as proceeds from employee stock awards and the related tax benefit. The Company is authorized to make purchases of its common stock using general corporate funds through open market purchases, pursuant to a Rule 10b5-1 plan or in privately negotiated transactions. In February 2018, the Company entered into an ASR transaction with a counterparty to pay an aggregate of $750.0 million in exchange for the delivery of approximately 6.5 million shares of its common stock based on current market prices. The purchase price per share under the ASR was based on the volume-weighted average price of the Company's common stock during the term of the ASR, less a discount. The ASR was entered into pursuant to the Company's existing share repurchase program. Final settlement of the ASR agreement was completed in April 2018 and the Company received delivery of an additional 1.6 million additional shares of its common stock. During the three months ended March 31, 2019, the Company expended approximately $93.8 million on open market purchases under the stock repurchase program, repurchasing 911,060 shares of common stock at an average price of $102.96. During the three months ended March 31, 2018, the Company had no additional open market purchases of its common stock. Shares for Tax Withholding During the three months ended March 31, 2019, the Company withheld 593,988 shares from equity awards that vested, totaling $60.1 million, to satisfy minimum tax withholding obligations that arose on the vesting of such equity awards. During the three months ended March 31, 2018, the Company withheld 507,274 shares from equity awards that vested, totaling $46.9 million, to satisfy minimum tax withholding obligations that arose on the vesting of such equity awards. These shares are reflected as treasury stock in the Company’s condensed consolidated balance sheets and the related cash outlays do not reduce the Company’s total stock repurchase authority.

TREASURY STOCK

Stock Repurchase Program

The Company’s Board of Directors authorized an ongoing stock repurchase program, of which $750.0 million was approved in October 2018. The Company may use the approved dollar authority to repurchase stock at any time until the approved amount is exhausted. The objective of the Company’s stock repurchase program is to improve stockholders’ returns. At March 31, 2019, approximately $674.1 million was available to repurchase common stock pursuant to the stock repurchase program. All shares repurchased are recorded as treasury stock. A portion of the funds used to repurchase stock over the course of the program was provided by net proceeds from the Convertible Notes and 2027 Notes offerings, as well as proceeds from employee stock awards and the related tax benefit. The Company is authorized to make purchases of its common stock using general corporate funds through open market purchases, pursuant to a Rule 10b5-1 plan or in privately negotiated transactions.

In February 2018, the Company entered into an ASR transaction with a counterparty to pay an aggregate of $750.0 million in exchange for the delivery of approximately 6.5 million shares of its common stock based on current market prices. The purchase price per share under the ASR was based on the volume-weighted average price of the Company's common stock during the term of the ASR, less a discount. The ASR was entered into pursuant to the Company's existing share repurchase program. Final settlement of the ASR agreement was completed in April 2018 and the Company received delivery of an additional 1.6 million additional shares of its common stock.

During the three months ended March 31, 2019, the Company expended approximately $93.8 million on open market purchases under the stock repurchase program, repurchasing 911,060 shares of common stock at an average price of $102.96.

During the three months ended March 31, 2018, the Company had no additional open market purchases of its common stock.

Shares for Tax Withholding

During the three months ended March 31, 2019, the Company withheld 593,988 shares from equity awards that vested, totaling $60.1 million, to satisfy minimum tax withholding obligations that arose on the vesting of such equity awards. During the three months ended March 31, 2018, the Company withheld 507,274 shares from equity awards that vested, totaling $46.9 million, to satisfy minimum tax withholding obligations that arose on the vesting of such equity awards. These shares are reflected as treasury stock in the Company’s condensed consolidated balance sheets and the related cash outlays do not reduce the Company’s total stock repurchase authority.