Stockholders' Equity (Narrative) (Details) - USD ($) shares in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 11, 2018
Stockholders' Equity Note [Abstract]
Payments of Dividends	$ 0	$ 0
Stock repurchase program, authorized amount			$ 300,000,000.0
Shares repurchased (in shares)	2.2
Shares repurchased, value	$ 50,100,000	$ 92,600,000

Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

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-Name Accounting Standards Codification
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