Fair value measurement - Summary of Changes in Fair Value of Pension Plan Assets and Liabilities Categorized as Level 3 (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation
Fair value of plan assets at beginning of period	$ 3,227,878
Fair value of plan assets at end of period	3,221,820	$ 3,227,878
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Fair value of plan liabilities at beginning of year	2,506
Fair value of plan liabilities at end of year	2,867	2,506
Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation
Fair value of plan assets at beginning of period	414,570	371,372
Relating to assets still held at report date	32,459	11,122
Relating to assets sold during the period	0	0
Purchases	45,046	78,693
Sales	(28,635)	(31,617)
Settlements	(25,204)	(15,000)
Fair value of plan assets at end of period	438,236	414,570
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Fair value of plan liabilities at beginning of year	2,008
Fair value of plan liabilities at end of year	2,008	2,008
Other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Fair value of plan liabilities at end of year	2,867
Other liabilities \| Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Fair value of plan liabilities at beginning of year	2,008
Relating to assets still held at report date	0
Relating to assets sold during the period	0
Purchases	0
Sales	0
Settlements	0
Fair value of plan liabilities at end of year	2,008	2,008
Derivative liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Fair value of plan liabilities at beginning of year	2,506
Fair value of plan liabilities at end of year		2,506
Derivative liabilities \| Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Fair value of plan liabilities at beginning of year	2,008	2,008
Relating to assets still held at report date		0
Relating to assets sold during the period		0
Purchases		0
Sales		0
Settlements		0
Fair value of plan liabilities at end of year		2,008
Real estate \| Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation
Fair value of plan assets at beginning of period	125,929	99,223
Relating to assets still held at report date	17,874	2,556
Relating to assets sold during the period	0	0
Purchases	9,082	24,150
Sales	(2,296)	0
Settlements	0	0
Fair value of plan assets at end of period	150,589	125,929
Partnership/joint venture interests \| Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation
Fair value of plan assets at beginning of period	174,789	149,018
Relating to assets still held at report date	7,607	2,845
Relating to assets sold during the period	0	0
Purchases	35,964	54,543
Sales	(26,339)	(31,617)
Settlements	(5,204)	0
Fair value of plan assets at end of period	186,817	174,789
Hedge funds \| Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation
Fair value of plan assets at beginning of period	113,850	123,126
Relating to assets still held at report date	6,978	5,724
Relating to assets sold during the period	0	0
Purchases	0	0
Sales	0	0
Settlements	(20,000)	(15,000)
Fair value of plan assets at end of period	100,828	113,850
Other assets \| Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation
Fair value of plan assets at beginning of period	2
Relating to assets still held at report date	0
Relating to assets sold during the period	0
Purchases	0
Sales	0
Settlements	0
Fair value of plan assets at end of period	2	2
Derivative contracts \| Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation
Fair value of plan assets at beginning of period	$ 2	5
Relating to assets still held at report date		(3)
Relating to assets sold during the period		0
Purchases		0
Sales		0
Settlements		0
Fair value of plan assets at end of period		$ 2

Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan from actual return (loss) on assets sold.

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Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan from actual return (loss) on assets still held.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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No definition available.

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

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- Definition

Amount, measured using unobservable input, of decrease in plan asset of defined benefit plan from sale.

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- Definition

Amount, measured using unobservable input, of decrease in plan asset of defined benefit plan from settlement of trade associated with underlying investment.

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- Definition

Amount, measured using unobservable input, of increase in plan asset of defined benefit plan from purchase.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

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Amount of gain (loss) recognized in other comprehensive income (OCI) from liability measured at fair value on recurring basis using unobservable input (level 3).

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- Definition

Amount of purchases of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sales of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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