Stock-Based Compensation Plans - PSRUs-settled activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Equity-settled PRSUs
Share-Based Compensation Plans
Granted	360,609	554
Weighted-average grant-date fair value	$ 38.87	$ 31,563.000
PRSUs compensation expense	$ 5,407	$ 4,674
Income tax expense (benefit)	(5,492)	(276)
Unrecognized compensation expense	$ 53,508
Weighted-average recognition period for unrecognized compensation expense	2 years 1 month 21 days
Cash-settled PRSUs
Share-Based Compensation Plans
PRSUs compensation expense	$ 10	100
Income tax expense (benefit)	3	$ (14)
Unrecognized compensation expense	$ 228
Weighted-average recognition period for unrecognized compensation expense	9 months
RSU
Share-Based Compensation Plans
Granted	465,222
Weighted-average grant-date fair value	$ 38.87
PRSUs compensation expense	$ 315
Income tax expense (benefit)	(71)
Unrecognized compensation expense	$ 17,836
Weighted-average recognition period for unrecognized compensation expense	2 years 11 months 16 days

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

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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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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