Stock-Based Compensation Plans - PSRUs-settled activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Equity-settled PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PRSUs (equity-settled) granted (in shares)	0	0	360,609	776,603
Weighted-average grant-date fair value, equity settled (in dollars per share)	$ 0	$ 0	$ 38.87	$ 21.65
PRSUs compensation expense	$ 6,778	$ 7,136	$ 19,577	$ 18,807
Cash Settled PSRUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PRSUs (cash-settled) granted (in shares)	0	0	0	0
Weighted-average grant-date fair value, cash settled (in dollars per share)	$ 0	$ 0	$ 0	$ 0
PRSUs compensation expense	$ (130)	$ 219	$ 476	$ 738
RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PRSUs (equity-settled) granted (in shares)	0	0	493,878	0
Weighted-average grant-date fair value, equity settled (in dollars per share)	$ 0	$ 0	$ 38.91	$ 0
PRSUs compensation expense	$ 1,684	$ 0	$ 3,674	$ 0

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Gross number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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