Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock available for issuance (in shares)	880,000
Term of stock options granted under Plan	10 years
Vesting period, generally, for stock options granted under the plan	3 years
Share based compensation costs	$ 4,000	$ 3,100	$ 2,800
Tax benefit of share-based compensation	$ 1,600	$ 1,200	$ 1,100
Forfeiture rate assumed	7.34%	7.13%	7.50%
Weighted average grant date fair value for stock options granted (in dollars per share)	$ 22.68	$ 22.89	$ 15.83
Weighted average grant date fair value for stock options vested (in dollars per share)	$ 17.83	$ 13.59	$ 10.29
Total intrinsic value of stock options exercised	$ 2,400	$ 13,000	$ 10,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	6 years 4 months 24 days	6 years 6 months	6 years 10 months 24 days
Interest rate	1.52%	2.16%	1.22%
Volatility	36.86%	37.15%	37.82%
Expected dividend yield	0.33%	0.34%	0.48%
Stock Options [Roll Forward]
Balance, beginning of year (in shares)	951,079
Granted (in shares)	238,773
Exercised (in shares)	(74,839)
Canceled (in shares)	(23,169)
Balance, end of year (in shares)	1,091,844	951,079
Exercisable, end of year (in shares)	737,985
Weighted Average Exercise Price Per Share [Abstract]
Balance, beginning of year (in dollars per share)	$ 37.46
Granted (in dollars per share)	60.40
Exercised (in dollars per share)	33.12
Canceled (in dollars per share)	60.22
Balance, end of year (in dollars per share)	42.29	$ 37.46
Exercisable, end of year (in dollars per share)	$ 35.13
Weighted Average Remaining Contractual Life [Abstract]
Outstanding options, end of year	6 years 5 months 16 days
Exercisable options, end of year	5 years 5 months 16 days
Aggregate Intrinsic Value [Abstract]
Outstanding options, end of year	$ 9,100
Exercisable options, end of year	$ 8,900
Closing stock price on last business day of the period (in dollars per share)	$ 45.86
Weighted average intrinsic value of options exercised (in dollars per share)	$ 32.07	$ 40.17	$ 20.03
Unrecognized stock-based compensation expense	$ 3,600
Weighted average period over which unrecognized stock-based compensation expense is expected to be recognized	3 years
Nonvested Stock Options [Member]
Stock Options [Roll Forward]
Balance, beginning of year (in shares)	319,592
Granted (in shares)	238,773
Vested (in shares)	(181,337)
Canceled (in shares)	(23,169)
Balance, end of year (in shares)	353,859	319,592
Weighted Average Exercise Price Per Share [Abstract]
Balance, beginning of year (in dollars per share)	$ 49.13
Granted (in dollars per share)	60.40
Vested (in dollars per share)	46.88
Canceled (in dollars per share)	60.22
Balance, end of year (in dollars per share)	$ 57.21	$ 49.13
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation costs	$ 8,800	$ 4,900	$ 3,900
Stock Options [Roll Forward]
Exercised (in shares)	(59,801)	(61,621)	(61,981)
Canceled (in shares)	(47,944)	(55,038)	(48,332)
Aggregate Intrinsic Value [Abstract]
Unrecognized stock-based compensation expense	$ 8,400
Weighted average period over which unrecognized stock-based compensation expense is expected to be recognized	3 years
Restricted Stock [Roll Forward]
Balance, beginning of year (in shares)	175,029	185,572	183,660
Granted (in shares)	216,502	106,116	112,225
Vested (in shares)	(59,801)
Canceled (in shares)	(47,944)
Balance, end of year (in shares)	283,786	175,029	185,572
Weighted Average Grant Date Fair Value [Abstract]
Balance, beginning of year (in dollars per share)	$ 50.56	$ 37.65	$ 31.25
Granted (in dollars per share)	60.32	58.94	41.44
Vested (in dollars per share)	47.51	36.51	28.09
Canceled (in dollars per share)	51.43	38.73	31.59
Balance, end of year (in dollars per share)	$ 58.63	$ 50.56	$ 37.65
Reversals of compensation expense related to restricted stock forfeitures	$ 1,600	$ 2,100	$ 100