In Millions, unless otherwise specified | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 1 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 2 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 | Level 3 |
| | | | Cash and cash equivalents | Cash and cash equivalents | Equity securities U.S.-based companies | Equity securities U.S.-based companies | Equity securities International-based companies | Equity securities International-based companies | Government bonds | Government bonds | Corporate bonds and debt securities | Corporate bonds and debt securities | Mutual, pooled and commingled funds | Mutual, pooled and commingled funds | Hedge funds/limited partnerships | Hedge funds/limited partnerships | Real estate | Real estate | Other | Other | | | | Cash and cash equivalents | Cash and cash equivalents | Equity securities U.S.-based companies | Equity securities U.S.-based companies | Equity securities International-based companies | Equity securities International-based companies | Government bonds | Government bonds | Corporate bonds and debt securities | Corporate bonds and debt securities | Mutual, pooled and commingled funds | Mutual, pooled and commingled funds | Hedge funds/limited partnerships | Hedge funds/limited partnerships | Real estate | Real estate | Other | Other | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member] | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits | Other postretirement benefits |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Cash and cash equivalents | Cash and cash equivalents | Equity securities U.S.-based companies | Equity securities U.S.-based companies | Equity securities International-based companies | Equity securities International-based companies | Government bonds | Government bonds | Corporate bonds and debt securities | Corporate bonds and debt securities | Mutual, pooled and commingled funds | Mutual, pooled and commingled funds | Hedge funds/limited partnerships | Hedge funds/limited partnerships | Real estate | Real estate | Other | Other | | | Cash and cash equivalents | Cash and cash equivalents | Equity securities U.S.-based companies | Equity securities U.S.-based companies | Equity securities International-based companies | Equity securities International-based companies | Government bonds | Government bonds | Corporate bonds and debt securities | Corporate bonds and debt securities | Mutual, pooled and commingled funds | Mutual, pooled and commingled funds | Hedge funds/limited partnerships | Hedge funds/limited partnerships | Real estate | Real estate | Other | Other | | | Cash and cash equivalents | Cash and cash equivalents | Equity securities U.S.-based companies | Equity securities U.S.-based companies | Equity securities International-based companies | Equity securities International-based companies | Government bonds | Government bonds | Corporate bonds and debt securities | Corporate bonds and debt securities | Mutual, pooled and commingled funds | Mutual, pooled and commingled funds | Hedge funds/limited partnerships | Hedge funds/limited partnerships | Real estate | Real estate | Other | Other | | | Cash and cash equivalents | Cash and cash equivalents | Equity securities U.S.-based companies | Equity securities U.S.-based companies | Equity securities International-based companies | Equity securities International-based companies | Government bonds | Government bonds | Corporate bonds and debt securities | Corporate bonds and debt securities | Mutual, pooled and commingled funds | Mutual, pooled and commingled funds | Hedge funds/limited partnerships | Hedge funds/limited partnerships | Real estate | Real estate | Other | Other | | | Cash and cash equivalents | Cash and cash equivalents | Equity securities | Equity securities | Equity securities U.S.-based companies | Equity securities U.S.-based companies | Equity securities International-based companies | Equity securities International-based companies | Government bonds | Government bonds | Corporate bonds and debt securities | Corporate bonds and debt securities | Mutual, pooled and commingled funds | Mutual, pooled and commingled funds | Hedge funds/limited partnerships | Hedge funds/limited partnerships | Real estate | Real estate | Other | Other | | | Cash and cash equivalents | Cash and cash equivalents | Equity securities U.S.-based companies | Equity securities U.S.-based companies | Equity securities International-based companies | Equity securities International-based companies | Government bonds | Government bonds | Corporate bonds and debt securities | Corporate bonds and debt securities | Mutual, pooled and commingled funds | Mutual, pooled and commingled funds | Hedge funds/limited partnerships | Hedge funds/limited partnerships | Real estate | Real estate | Other | Other |