Years ended December 31,

2021

2022

2023

(In thousands)

Accumulated other comprehensive loss, net of tax:

Currency translation:

Balance at beginning of period

$

(169,575)

$

(171,235)

$

(178,191)

Other comprehensive income (loss)

(1,660)

(6,956)

1,072

Balance at end of period

$

(171,235)

$

(178,191)

$

(177,119)

Defined benefit pension plans:

Balance at beginning of period

$

(80,704)

$

(68,468)

$

(43,857)

Other comprehensive income (loss):

Amortization of prior service cost and net losses included in
net periodic pension cost

4,813

3,592

1,436

Net actuarial gain (loss) arising during the year

7,423

20,881

(3,094)

Plan settlement

—

138

4,142

Balance at end of period

$

(68,468)

$

(43,857)

$

(41,373)

OPEB plans:

Balance at beginning of period

$

(910)

$

(1,053)

$

(893)

Other comprehensive income (loss):

Amortization of net gain included in net periodic
OPEB cost

(143)

(369)

(357)

Net actuarial gain arising during the year

—

529

136

Balance at end of period

$

(1,053)

$

(893)

$

(1,114)

Marketable debt securities:

Balance at beginning of period

$

—

$

—

$

(50)

Other comprehensive income (loss) - unrealized gain (loss)
arising the period.

—

(50)

35

Balance at end of period

$

—

$

(50)

$

(15)

Total accumulated other comprehensive loss:

Balance at beginning of period

$

(251,189)

$

(240,756)

$

(222,991)

Other comprehensive income

10,433

17,765

3,370

Balance at end of period

$

(240,756)

$

(222,991)

$

(219,621)