Share-Based Compensation - Cash-settled Restricted Stock Activity (Details) - Cash-settled Restricted Stock	3 Months Ended
	Mar. 31, 2016 $ / shares shares
Shares
Unvested, Beginning balance (in shares) | shares	110,860
Granted (in shares) | shares	39,100
Vested (in shares) | shares	(33,920)
Forfeited (in shares) | shares	(4,250)
Unvested, Ending balance (in shares) | shares	111,790
Weighted-Average Grant Date Fair Value
Unvested, Beginning balance (in dollars per share) | $ / shares	$ 76.61
Granted (in dollars per share) | $ / shares	82.88
Vested (in dollars per share) | $ / shares	71.81
Forfeited (in dollars per share) | $ / shares	82.88
Unvested, Ending balance (in dollars per share) | $ / shares	$ 82.88