Schedule of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	$ 127.5	$ (51.0)	$ 16.1
Recognition and Measurement of Financial Assets and Financial Liabilities, Reclassification from AOCI to Retained Earnings	(17.5)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(910.6)	205.6	(52.5)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	(13.6)	(27.1)	(14.6)
Total Other Comprehensive Income (Loss)	(924.2)	178.5	(67.1)
Balance at End of Year	(814.2)	127.5	(51.0)
Net Unrealized Gain (Loss) on Securities
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	607.8	440.6	204.3
Recognition and Measurement of Financial Assets and Financial Liabilities, Reclassification from AOCI to Retained Earnings	(17.5)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(920.3)	176.7	226.5
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	17.6	(9.5)	9.8
Total Other Comprehensive Income (Loss)	(902.7)	167.2	236.3
Balance at End of Year	(312.4)	607.8	440.6
Net Gain on Hedges
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	282.3	327.5	378.0
Recognition and Measurement of Financial Assets and Financial Liabilities, Reclassification from AOCI to Retained Earnings	0.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	16.8	(14.7)	(15.8)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	(48.5)	(30.5)	(34.7)
Total Other Comprehensive Income (Loss)	(31.7)	(45.2)	(50.5)
Balance at End of Year	250.6	282.3	327.5
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(254.5)	(354.0)	(173.6)
Recognition and Measurement of Financial Assets and Financial Liabilities, Reclassification from AOCI to Retained Earnings	0.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(50.7)	99.5	(180.4)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	0.0	0.0	0.0
Total Other Comprehensive Income (Loss)	(50.7)	99.5	(180.4)
Balance at End of Year	(305.2)	(254.5)	(354.0)
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(508.1)	(465.1)	(392.6)
Recognition and Measurement of Financial Assets and Financial Liabilities, Reclassification from AOCI to Retained Earnings	0.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	43.6	(55.9)	(82.8)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	17.3	12.9	10.3
Total Other Comprehensive Income (Loss)	60.9	(43.0)	(72.5)
Balance at End of Year	$ (447.2)	$ (508.1)	$ (465.1)