Share-Based Compensation - Cash-settled Restricted Stock Activity (Details) - Cash-settled Restricted Stock	6 Months Ended
	Jun. 30, 2016 $ / shares shares
Shares
Unvested, Beginning balance (in shares) | shares	110,860
Granted (in shares) | shares	39,450
Vested (in shares) | shares	(35,750)
Forfeited (in shares) | shares	(7,340)
Unvested, Ending balance (in shares) | shares	107,220
Weighted-Average Grant Date Fair Value
Unvested, Beginning balance (in dollars per share) | $ / shares	$ 76.61
Granted (in dollars per share) | $ / shares	82.10
Vested (in dollars per share) | $ / shares	72.41
Forfeited (in dollars per share) | $ / shares	82.10
Unvested, Ending balance (in dollars per share) | $ / shares	$ 82.10