Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	300,000,000	300,000,000
Common stock, issued (in shares)	139,857,673	139,656,674
Common stock outstanding (in shares)	133,508,212	134,874,302
Treasury stock (in shares)	6,349,461	4,782,372

Face amount or stated value per share of common stock.

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- Definition

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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