Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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The cash outflow for cost incurred directly with the issuance of an equity security.

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The cash inflow from the issuance of common stock, preferred stock, treasury stock, stock options, and other types of equity.

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The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

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Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

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Gross number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP). Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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Number of share options (or share units) exercised during the current period.

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Organization - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions						3 Months Ended
	May 23, 2019	Apr. 03, 2019	Mar. 22, 2019	Nov. 16, 2018	Apr. 30, 2018	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Common stock shares issued		14,222,142		12,650,000	24,150,000	141,942,066		139,453,710
Proceeds from shares issued in IPO and private placement					$ 631.3
IPO [Member]
Shares issued					21,000,000
Shares issued, price per share					$ 22.00
Private Placement [Member]
Shares issued					4,545,455
Shares issued, price per share					$ 22.00
Underwriter [Member]
Stock option exercised			1,950,000	1,650,000	3,150,000
Issuance of common stock upon exercise of options, shares		1,222,142
Secondary Offering [Member]
Shares issued	8,000,000		13,000,000	11,000,000
Shares issued, price per share	$ 50.50		$ 50.50	$ 36.00
Secondary Offering [Member] \| Selling, General and Administrative Expense [Member]
Offering costs						$ 0.8	$ 0.9	$ 1.3