Subsequent Event - Additional Information (Detail) - $ / shares |
1 Months Ended | 3 Months Ended | 12 Months Ended | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Jan. 31, 2018 |
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2016 |
Sep. 30, 2016 |
Jun. 30, 2016 |
Mar. 31, 2016 |
Dec. 31, 2015 |
Sep. 30, 2015 |
Jun. 30, 2015 |
Mar. 31, 2015 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
Subsequent Event [Line Items] | ||||||||||||||||
Common stock dividends per share declared (in dollars per share) | $ 0.10 | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.40 | $ 0.40 | $ 0.40 | |
Subsequent Event [Member] | ||||||||||||||||
Subsequent Event [Line Items] | ||||||||||||||||
Common stock dividends per share declared (in dollars per share) | $ 0.10 |