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STOCKHOLDERS' EQUITY AND EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2015 | Jun. 30, 2014 | Jun. 30, 2015 | Jun. 30, 2014 | Jan. 16, 2014
Quarterly Dividends |  |  |  |  |
Dividends for common stock declared (in dollars per share) | $ 0.20 | $ 0.18 | $ 0.40 | $ 0.36 |
MetroCorp |  |  |  |  |
Class of Stock |  |  |  |  |
Number of shares under warrant |  |  |  |  | 771,429
Common Stock |  |  |  |  |
Class of Stock |  |  |  |  |
Amount of stock repurchase approved by the Board of Directors | $ 100.0 |  | $ 100.0 |  |
Quarterly Dividends |  |  |  |  |
Dividends for common stock declared (in dollars per share) | $ 0.20 |  |  |  |
Common stock cash dividends paid | $ 29.0 | $ 26.0 | $ 58.0 | $ 52.0 |
Common Stock | MetroCorp |  |  |  |  |
Class of Stock |  |  |  |  |
Number of shares under warrant | 230,282 |  | 230,282 |  |

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