XML 199 R183.htm IDEA: XBRL DOCUMENT v3.7.0.1
Note Stock-based compensation (Summary of restricted stock activity under the incentive plan for members of the Board of Directors) (Detail) - Restricted Stock Units (RSUs) - Directors - $ / shares
3 Months Ended 12 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Roll Forward      
Beginning Balance 0 0 0
Granted 0 2,338 40,517
Vested 0   (40,517)
Forfeited 0   0
Ending Balance 0   0
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Additional Disclosures Abstract      
Non-vested at beginning of period $ 0 $ 0 $ 0
Granted 0   29.77
Vested 0   29.77
Forfeited 0   0
Non-vested at end of period $ 0   $ 0