The contribution will "significantly address" the underfunding of the plan, which, as of Dec. 31, had a funding ratio of 75.8%.
Employees can save money to pay for health care in retirement through health savings accounts, but they also need to be financially sound overall.
Low interest rates have pushed equities up for years, making a passive investment strategy a winner.
CFOs may not focus much attention on workers' financial wellness, but they pay a price when elderly employees simply can't afford to retire.
Older employees who cannot afford to retire can present a costly challenge for the entire company.
If the corporate tax rate is lowered, funding more future liabilities before the change takes effect could net significant savings for plan sponsors.
The deal comes as insurers are buying pension plans at a record rate.
For most penison-plan sponsors, it's as simple as making a scheduled contribution a month early.
By the end of 2017, public companies will have to separate employee service costs from other pension cost components.