Capital Stock (Details) $ / shares in Units, shares in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2020 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) vote shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)
Equity [Abstract]
Authorized share capital (in shares) | shares		233,333	233,333
Number of votes per share		1
Shareholder ownership threshold for voting rights		9.50%
Maximum number of votes per share for certain shareholders under 9.5% shareholder provision		1
Minimum number of votes per share for other shareholders under 9.5% shareholder provision		1
Common shares, issued (in shares) | shares	13,800	112,423	98,394
Share price (in dollars per share) | $ / shares	$ 33.25
Net proceeds from sale of stock | $	$ 440,000	$ 439,962	$ 0	$ 0