Summary of Significant Accounting Policies (Details 6) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Abstract]
Number of stock options granted	142,908	175,632	245,424
Weighted average grant date fair value of stock options granted	$ 11.18	$ 9.01	$ 8.25
Weighted average assumptions:
Risk-free interest rate	1.70%	1.90%	1.00%
Expected dividend yield	2.60%	2.50%	2.70%
Expected life, in years	7 years 2 months 12 days	5 years 8 months 12 days	5 years 9 months 18 days
Expected volatility (based on historical volatility)	42.80%	40.30%	54.50%