Stock-Based Compensation and Stock Awards - Summary of PSA Activity (Detail) - Performance Unit Awards [Member]	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Number of shares
Nonvested options, Beginning Balance (in shares) | shares	135,969
Granted (in shares) | shares	87,503
Vested (in shares) | shares	(27,253)
Forfeited (in shares) | shares	0
Nonvested options, Ending Balance (in shares) | shares	196,219
Weighted Average Grant Date Fair Value Per Unit
Nonvested Weighted Average Grant Date Fair Value, Beginning Balance (in dollars per share) | $ / shares	$ 106.49
Granted (in dollars per share) | $ / shares	53.46
Vested (in dollars per share) | $ / shares	138.31
Forfeited (in dollars per share) | $ / shares	0.00
Nonvested Weighted Average Grant Date Fair Value, Ending Balance (in dollars per share) | $ / shares	$ 78.42