Stockholders' Equity and Earnings Per Common Share Treasury Stock Transactions (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Equity, Class of Treasury Stock
Number of Treasury Shares Repurchased	2.7	1.9
Cost of Shares Repurchased	$ 100.0	$ 100.2
Shares repurchased cost Commissions		$ 0.2
Repurchase Program Authorized in May 2018
Equity, Class of Treasury Stock
Authorized Stock Repurchases	750.0
Remaining Authorized Share Repurchases	400.0
Repurchase Program Authorized in May 2017
Equity, Class of Treasury Stock
Authorized Stock Repurchases	$ 750.0

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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