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Common Stock - Summary of Information Regarding Outstanding SARs (Detail) - Stock Appreciation Rights (SARs) [Member] - $ / shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Restricted Shares Outstanding, Beginning balance 1,399,302 1,493,689
Granted 7,088 14,228
Forfeited (76,133) (83,124)
Exercised   (25,491)
Restricted Shares Outstanding, Ending balance 1,330,257 1,399,302
Exercisable at end of year 1,315,701 165,755
Weighted-Average Grant Date Fair Value of Restricted Stock, Beginning Balance $ 28.49 $ 28.41
Granted 28.72 35.09
Forfeited 29.18 28.32
Exercised   42.61
Weighted-Average Grant Date Fair Value of Restricted Stock, Ending Balance 28.45 28.49
Average Exercise Price, Exercisable at end of year $ 28.40 $ 28.57