Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares  | 
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015  | 
Dec. 31, 2014  | 
Dec. 31, 2013  | 
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| Increase (Decrease) in Stockholders' Equity [Roll Forward] | |||
| Dividends declared per share (in dollars per share) | $ 0.43 | $ 0.39 | $ 0.35 | 
| X | ||||||||||
- Definition Aggregate dividends declared during the period for each share of common stock outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available. 
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