Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation (RSU Equity Awards (Details)

v3.20.4
Share-Based Compensation (RSU Equity Awards (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
RSU equity awards      
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]      
Unvested at the beginning of the period (in shares) 269,000 210,000 179,000
Granted (in shares) 562,000 188,000 87,000
Vested (in shares) (132,000) (106,000) (51,000)
Forfeited (in shares) (22,000) (23,000) (5,000)
Unvested at the end of the period (in shares) 677,000 269,000 210,000
Weighted Average Grant-Date Fair Value per Share      
Unvested at the beginning of the period, Grant Date Fair Value per Share (usd per share) $ 102.48 $ 130.39 $ 115.36
Granted, grant date fair value per share (usd per share) 21.07 85.96 144.86
Vested, grant date fair value per share (usd per share) 105.14 126.75 103.83
Forfeited, grant date fair value per share (usd per share) 96.84 110.55 114.32
Unvested at the end of the period, grant date fair value per share (usd per share) $ 34.57 $ 102.48 $ 130.39
Fair value of shares vested $ 1.6 $ 7.3 $ 6.3
RSU equity awards | Vesting range 0 to 200%      
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]      
Unvested at the beginning of the period (in shares) 39,900 20,800  
Unvested at the end of the period (in shares) 111,200 39,900 20,800
RSU equity awards | Vesting Minimum      
Weighted Average Grant-Date Fair Value per Share      
Share-based compensation arrangement vesting rights, percentage 0.00% 0.00% 0.00%
RSU equity awards | Vesting Maximum      
Weighted Average Grant-Date Fair Value per Share      
Share-based compensation arrangement vesting rights, percentage 300.00% 200.00% 200.00%
Performance-based RSU      
Weighted Average Grant-Date Fair Value per Share      
Fair value of shares vested $ 3.4 $ 4.3 $ 3.5