Equity Incentive Awards (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

A summary of our restricted stock activity, and related information for the years ended December 31, 2016, 2015, and 2014 follows:

	Number of Shares		Weighted Average Grant Date Fair Value
Balance at December 31, 2013	99,788		$	37.17
Shares granted	186,666		42.61
Shares vested	(184,229	)	40.49
Balance at December 31, 2014	102,225		41.09
Shares granted	158,014		54.68
Shares vested	(174,739	)	49.17
Balance at December 31, 2015	85,500		49.72
Shares granted	133,726		68.21
Shares vested	(153,619	)	59.85
Balance at December 31, 2016	65,607		63.68

Summary of Stock Option Activity

A summary of our stock option activity, and related information for the years ended December 31, 2016, 2015 and 2014 follows:

	Shares Subject To Options		Weighted Average Exercise Price Per Share		Weighted Average Outstanding Contractual Life (in years)
Balance at December 31, 2014	1,085,600		$	21.95	2.1
Options exercised	(220,000	)	17.35
Balance at December 31, 2015	865,600		23.12		1.6
Options issued	7,550		74.53
Options exercised	(440,000	)	25.66
Balance at December 31, 2016	433,150		21.44		1.7
Exercisable at December 31, 2016	427,836		20.79		1.6

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The fair value of each grant is estimated on the grant date using the Black-Scholes-Merton model. The following table includes the assumptions that were made and the estimated fair values:                

	2016
Dividend Yield	2.3		%
Risk-free interest rate	1.3		%
Expected Life	6 years
Expected Volatility	19.8		%
Estimated Grant Date Fair Value of Options	$	80,751