Stockholders' Equity and Earnings Per Common Share Treasury Stock Transactions (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Equity, Class of Treasury Stock
Number of Treasury Shares Repurchased	2.1	3.7
Cost of Shares Repurchased	$ 100.0	$ 100.0
Commission Paid on Common Stock Repurchased	0.0	$ 0.0
Repurchase Program Authorized in May 2016
Equity, Class of Treasury Stock
Authorized Stock Repurchases	750.0
Remaining Authorized Share Repurchases	395.5
Repurchase Program Authorized in May 2015
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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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