Stock-Based Compensation and Stock Awards - Schedule of DSA Activity (Detail) - DSA [Member]	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Number of shares
Nonvested options, Beginning Balance (in shares) | shares	6,162
Granted (in shares) | shares	8,174
Vested (in shares) | shares	(914)
Forfeited (in shares) | shares	0
Nonvested options, Ending Balance (in shares) | shares	13,422
Weighted Average Grant Date Fair Value Per Unit
Nonvested Weighted Average Grant Date Fair Value, Beginning Balance (in dollars per share) | $ / shares	$ 71.77
Granted (in dollars per share) | $ / shares	58.47
Vested (in dollars per share) | $ / shares	89.39
Forfeited (in dollars per share) | $ / shares	0.00
Nonvested Weighted Average Grant Date Fair Value, Ending Balance (in dollars per share) | $ / shares	$ 62.46