|
Pension Plans and Other Postretirement Benefits - Schedule of Net Periodic Benefit Costs for Pension and Other Postretirement Benefit Plans (Detail) (USD $)
In Thousands, unless otherwise specified
|
12 Months Ended |
|
Dec. 31, 2014
|
Dec. 31, 2013
|
Dec. 31, 2012
|
| Defined Benefit Pension Plans [Member] |
|
|
|
| Net periodic benefit cost |
|
|
|
| Service cost |
$ 14,097 |
$ 13,866 |
$ 10,054 |
| Interest cost |
7,687 |
6,482 |
6,475 |
| Expected return on plan assets |
(2,427) |
(1,710) |
(2,251) |
| Amortization of prior service cost (credit) |
(1,002) |
(989) |
142 |
| Amortization of net (gain) loss |
2,557 |
3,093 |
(630) |
| Settlement and curtailment (gain) loss |
1,517 |
2,122 |
(247) |
| Net periodic benefit cost (income) |
22,429 |
22,864 |
13,543 |
| Amounts recognized in other comprehensive income (loss) |
|
|
|
| Net loss (gain) |
56,318 |
6,170 |
65,303 |
| Amortization of prior service (cost) credit |
1,002 |
989 |
(142) |
| Amortization of net gain (loss) |
(2,557) |
(3,093) |
630 |
| Settlement and curtailment gain (loss) |
(1,517) |
(2,122) |
247 |
| Prior service cost (credit) |
(12,706) |
(12,992) |
|
| Total recognized in other comprehensive income (loss) |
40,540 |
(11,048) |
66,038 |
| Net periodic benefit cost (income) |
22,429 |
22,864 |
13,543 |
| Total recognized in net periodic benefit cost and other comprehensive income (loss) |
62,969 |
11,816 |
79,581 |
| Other Postretirement Benefit Plans [Member] |
|
|
|
| Net periodic benefit cost |
|
|
|
| Service cost |
1,048 |
283 |
252 |
| Interest cost |
1,189 |
262 |
275 |
| Amortization of prior service cost (credit) |
102 |
|
|
| Amortization of net (gain) loss |
(45) |
|
(9) |
| Settlement and curtailment (gain) loss |
(1,507) |
|
|
| Net periodic benefit cost (income) |
787 |
545 |
518 |
| Amounts recognized in other comprehensive income (loss) |
|
|
|
| Net loss (gain) |
1,263 |
(1,354) |
677 |
| Amortization of prior service (cost) credit |
(102) |
|
|
| Amortization of net gain (loss) |
45 |
|
9 |
| Settlement and curtailment gain (loss) |
(242) |
|
|
| Prior service cost (credit) |
|
730 |
|
| Total recognized in other comprehensive income (loss) |
964 |
(624) |
686 |
| Net periodic benefit cost (income) |
787 |
545 |
518 |
| Total recognized in net periodic benefit cost and other comprehensive income (loss) |
$ 1,751 |
$ (79) |
$ 1,204 |