Common Stock	6 Months Ended
Jun. 30, 2020
Stockholders' Equity Note [Abstract]
Common Stock	Note 6 – Common Stock Follow-on Public Offerings In September 2018, the Company entered into a follow-on public offering of 3,500,000 shares of common stock in connection with a forward sale agreement (the “September 2018 Forward”). The September 2018 Forward was settled in its entirety in April 2019. Upon settlement, the Company issued 3,500,000 shares of common stock and received net proceeds of $186.0 million, after deducting fees and expenses. In April 2019, the Company entered into a follow-on public offering (the “April 2019 Forward”) to sell an aggregate of 3,162,500 shares of common stock, which included the full exercise of the underwriters’ option to purchase an additional 412,500 shares of common stock. The April 2019 Forward was settled in its entirety in December 2019. Upon settlement, the Company issued 3,162,500 shares of common stock and received net proceeds of approximately $195.8 million, after deducting fees and expenses. In April 2020, the Company completed a follow-on public offering of 2,875,000 shares of common stock, which included the full exercise of the underwriters’ option to purchase an additional 375,000 shares of common stock. Upon closing the Company issued 2,875,000 shares of common stock and received net proceeds of $170.4 million, after deducting fees and expenses. Also in April 2020, the Company entered into a follow-on public offering (the “April 2020 Forward”) to sell an aggregate of 6,166,666 shares of common stock in connection with a forward sale agreement. As of June 30, 2020, the Company has not received proceeds from the sale of shares of its common stock by the forward purchaser. The April 2020 Forward is required to be settled no later than April 20, 2021. ATM Programs 2019 ATM Program In July 2019, the Company entered into a $400.0 million ATM program (the “2019 ATM Program”) through which the Company, from time to time, sold shares of common stock. During the third quarter of 2019, the Company issued 444,228 shares of common stock under the 2019 ATM Program, at an average price of $74.30, realizing gross proceeds of $33.0 million. In addition to selling shares of common stock, the Company also entered into forward sale agreements through the 2019 ATM Program, as described below. During the fourth quarter of 2019, the Company entered into forward sale agreements in connection with the 2019 ATM Program to sell an aggregate of 2,003,118 shares of common stock. Additionally, during the first quarter of 2020, the Company entered into forward sale agreements in connection with the 2019 ATM Program to sell an aggregate of 3,169,754 shares of common stock. During the six months ended June 30, 2020, the Company settled all forward sale agreements under the 2019 ATM Program, realizing gross proceeds of $254.3 million. The 2019 ATM Program was terminated simultaneously with the establishment of the 2020 ATM Program, which is discussed below. As a result, no future issuances will occur under the 2019 ATM Program. 2020 ATM Program In March 2020, the Company entered into a new $400.0 million ATM program (the “2020 ATM Program”) through which the Company, from time to time, may sell shares of common stock. In addition to selling shares of common stock, the Company has entered into forward sale agreements through the 2020 ATM Program, as described below. During the first quarter of 2020, the Company entered into a forward sale agreement to sell an aggregate of 204,074 shares of common stock. During the six months ended June 30, 2020, the Company settled this forward sale agreement realizing gross proceeds of $12.7 million. During the second quarter of 2020, the Company entered into forward sale agreements to sell an aggregate of 742,860 shares of common stock. As of June 30, 2020, no shares have been settled under the 2020 ATM Program. The Company is required to settle outstanding shares under the 2020 ATM Program by various dates between April and June 2021. After considering the 742,860 shares of common stock subject to forward sale agreements and including prior shares issued under the 2020 ATM Program, the Company had approximately $337.8 million of availability remaining under the 2020 ATM Program as of June 30, 2020. 2018 ATM Program In May 2018, the Company entered into a $250.0 million ATM program (“2018 ATM Program”) through which the Company, from time to time, sold shares of common stock and entered into forward sale agreements. During the six months ended June 30, 2019, the Company issued 886,768 shares of common stock under the 2018 ATM Program, realizing gross proceeds of approximately $59.3 million. The 2018 ATM Program was subsequently terminated, and no future issuances will occur under the 2018 ATM Program.

Common Stock

6 Months Ended

Jun. 30, 2020

Stockholders' Equity Note [Abstract]

Note 6 – Common Stock

Follow-on Public Offerings

In September 2018, the Company entered into a follow-on public offering of 3,500,000 shares of common stock in connection with a forward sale agreement (the “September 2018 Forward”). The September 2018 Forward was settled in its entirety in April 2019. Upon settlement, the Company issued 3,500,000 shares of common stock and received net proceeds of $186.0 million, after deducting fees and expenses.

In April 2019, the Company entered into a follow-on public offering (the “April 2019 Forward”) to sell an aggregate of 3,162,500 shares of common stock, which included the full exercise of the underwriters’ option to purchase an additional 412,500 shares of common stock. The April 2019 Forward was settled in its entirety in December 2019. Upon settlement, the Company issued 3,162,500 shares of common stock and received net proceeds of approximately $195.8 million, after deducting fees and expenses.

In April 2020, the Company completed a follow-on public offering of 2,875,000 shares of common stock, which included the full exercise of the underwriters’ option to purchase an additional 375,000 shares of common stock. Upon closing the Company issued 2,875,000 shares of common stock and received net proceeds of $170.4 million, after deducting fees and expenses.

Also in April 2020, the Company entered into a follow-on public offering (the “April 2020 Forward”) to sell an aggregate of 6,166,666 shares of common stock in connection with a forward sale agreement. As of June 30, 2020, the Company has not received proceeds from the sale of shares of its common stock by the forward purchaser. The April 2020 Forward is required to be settled no later than April 20, 2021.

ATM Programs

2019 ATM Program

In July 2019, the Company entered into a $400.0 million ATM program (the “2019 ATM Program”) through which the Company, from time to time, sold shares of common stock. During the third quarter of 2019, the Company issued 444,228 shares of common stock under the 2019 ATM Program, at an average price of $74.30, realizing gross proceeds of $33.0 million. In addition to selling shares of common stock, the Company also entered into forward sale agreements through the 2019 ATM Program, as described below.

During the fourth quarter of 2019, the Company entered into forward sale agreements in connection with the 2019 ATM Program to sell an aggregate of 2,003,118 shares of common stock. Additionally, during the first quarter of 2020, the Company entered into forward sale agreements in connection with the 2019 ATM Program to sell an aggregate of 3,169,754 shares of common stock. During the six months ended June 30, 2020, the Company settled all forward sale agreements under the 2019 ATM Program, realizing gross proceeds of $254.3 million.

The 2019 ATM Program was terminated simultaneously with the establishment of the 2020 ATM Program, which is discussed below. As a result, no future issuances will occur under the 2019 ATM Program.

2020 ATM Program

In March 2020, the Company entered into a new $400.0 million ATM program (the “2020 ATM Program”) through which the Company, from time to time, may sell shares of common stock. In addition to selling shares of common stock, the Company has entered into forward sale agreements through the 2020 ATM Program, as described below.

During the first quarter of 2020, the Company entered into a forward sale agreement to sell an aggregate of 204,074 shares of common stock. During the six months ended June 30, 2020, the Company settled this forward sale agreement realizing gross proceeds of $12.7 million.

During the second quarter of 2020, the Company entered into forward sale agreements to sell an aggregate of 742,860 shares of common stock. As of June 30, 2020, no shares have been settled under the 2020 ATM Program. The Company is required to settle outstanding shares under the 2020 ATM Program by various dates between April and June 2021.

After considering the 742,860 shares of common stock subject to forward sale agreements and including prior shares issued under the 2020 ATM Program, the Company had approximately $337.8 million of availability remaining under the 2020 ATM Program as of June 30, 2020.

2018 ATM Program

In May 2018, the Company entered into a $250.0 million ATM program (“2018 ATM Program”) through which the Company, from time to time, sold shares of common stock and entered into forward sale agreements. During the six months ended June 30, 2019, the Company issued 886,768 shares of common stock under the 2018 ATM Program, realizing gross proceeds of approximately $59.3 million. The 2018 ATM Program was subsequently terminated, and no future issuances will occur under the 2018 ATM Program.