Outstanding Common Stock Equivalents That Were Anti-Dilutive Tickmarks (Detail) - $ / shares |
12 Months Ended | ||
---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
Earnings Per Share [Abstract] | |||
Anti-dilutive Non-Vested Stock Weighted Average Grant Date Fair Value | $ 48.66 | $ 38.40 | $ 52.07 |