CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares
3 Months Ended 6 Months Ended 12 Months Ended
Mar. 31, 2016
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2014
Jun. 30, 2014
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Statement Of Stockholders Equity [Abstract]                  
Cash dividends declared per share $ 0.07 $ 0.06 $ 0.06 $ 0.06 $ 0.14 $ 0.08 $ 0.29 $ 0.18 $ 0.22