Stock-Based Compensation (Details 3) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) item $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares
Additional information
Accrued compensation | $	$ 54,079	$ 44,683
Stock Options
Stock-Based Compensation
Weighted-average fair value per share of options granted (in dollars per share)	$ 6.33	$ 6.24	$ 5.06
Fair value assumptions:
Expected dividend yield (as a percent)	1.51%	1.34%	1.82%
Expected stock price volatility (as a percent)	38.40%	45.20%	46.60%
Risk-free interest rate (as a percent)	1.50%	1.91%	0.96%
Expected term	5 years 7 months 6 days	5 years 7 months 6 days	5 years 7 months 6 days
Other information
Vesting period	3 years
Total fair value of options vested | $	$ 800
Nonvested Options, Shares
Nonvested at beginning of year (in shares) | shares	323
Granted (in shares) | shares	132
Vested (in shares) | shares	(168)
Nonvested at end of year (in shares) | shares	287	323
Nonvested Options, Weighted-Average Grant Date Fair Value
Nonvested at beginning of year (in dollars per share)	$ 5.43
Granted (in dollars per share)	6.33	$ 6.24	$ 5.06
Vested (in dollars per share)	5.03
Nonvested at end of year (in dollars per share)	$ 6.07	5.43
Additional information
Compensation expense yet to be recognized | $	$ 700
Weighted-average period over which compensation cost will be recognized	1 year 8 months 12 days
Stock Options | Minimum
Other information
Sum of age and years of service for accelerated vesting on retirement of certain stock options and restricted stock awards	75 years
Restricted Stock and Restricted Stock Units
Stock-Based Compensation
Weighted-average fair value per share of options granted (in dollars per share)		20.64
Nonvested Options, Weighted-Average Grant Date Fair Value
Nonvested at beginning of year (in dollars per share)	$ 17.48	14.42
Granted (in dollars per share)		20.64
Vested (in dollars per share)		16.42
Forfeited (in dollars per share)		14.45
Nonvested at end of year (in dollars per share)		$ 17.48	14.42
Shares
Unvested at beginning of year (in shares) | shares	160
Granted (in shares) | shares	113
Vested (in shares) | shares	(121)
Forfeited (in shares) | shares	(3)
Unvested at end of year (in shares) | shares	149	160
Additional information
Compensation expense yet to be recognized | $	$ 1,200
Weighted-average period over which compensation cost will be recognized	1 year 9 months 18 days
Fair value of shares vested | $	$ 2,000
Weighted-average fair value (in dollars per share)	$ 20.64	$ 15.80	$ 13.57
Aggregate intrinsic value of stock vested | $	$ 3,400	$ 2,900	$ 4,700
Performance Stock Units
Other information
Vesting period	3 years
Additional information
Compensation expense yet to be recognized | $	$ 1,600
Weighted-average period over which compensation cost will be recognized	1 year 4 months 24 days
Period for which shareholder return is compared with peer group for units determined by EPS performance	3 years
Types of performance units | item	2
Percentage of units measured on stock price relative to peer group	50.00%
Percentage of units measured on stock price based on pre determined EPS	50.00%
Calculated fair market value | $	$ 5,200
Value of PSU's granted | $	2,000
Accrued compensation | $	$ 2,600	$ 1,800
Performance Stock Units | Minimum
Additional information
Performance measures for dollar denominated award granted	0
Performance Stock Units | Maximum
Additional information
Performance measures for dollar denominated award granted	2.0
Restricted Stock | Minimum
Other information
Sum of age and years of service for accelerated vesting on retirement of certain stock options and restricted stock awards	75 years