Stock-based Compensation Expense Activity in Non-Performance Based Restricted Stock Awards (Details) - Restricted Stock And Restricted Stock Units	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Shares
Nonvested, beginning of period (in shares) | shares	118,121
Granted (in shares) | shares	156,662
Vested (in shares) | shares	(53,875)
Forfeited (in shares) | shares	(40,252)
Nonvested, end of period (in shares) | shares	180,656
Weighted Average Grant Date Fair Value
Nonvested, beginning of period (in dollars per share) | $ / shares	$ 58.62
Granted (in dollars per share) | $ / shares	56.43
Vested (in dollars per share) | $ / shares	57.34
Forfeited (in dollars per share) | $ / shares	54.65
Nonvested, end of period (in dollars per share) | $ / shares	$ 57.99