Share-Based Compensation - Summary of Nonvested Stock Activity (Details) - Nonvested Stock Award - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2016	Apr. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost charged against income			$ 1,500	$ 1,200	$ 4,600	$ 4,200
Income tax benefit recognized during period			577	$ 454	1,800	$ 1,600
Unrecognized compensation cost	$ 19,200		$ 19,200		$ 19,200
Weighted-average period of recognition of unrecognized compensation expense					3 years 32 days
Shares
Outstanding, beginning balance (in shares)					417,000
Granted (in shares)					123,000
Vested (in shares)					(18,000)
Forfeited/Canceled (in shares)					(5,000)
Outstanding, ending balance (in shares)	517,000		517,000		517,000
Grant Date Weighted- Average Fair Value Per Share
Outstanding, beginning balance (in dollars per share)					$ 38.28
Granted (in dollars per share)					68.49
Vested (in dollars per share)					27.58
Forfeited/Canceled (in dollars per share)					39.05
Outstanding, ending balance (in dollars per share)	$ 45.83		$ 45.83		$ 45.83
Directors and Non-Executive Employees
Shares
Granted (in shares)					122,733
Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum vesting period of outstanding options and non vested shares (in years)					3 years
Shares
Granted (in shares)		4,992
Non-Executive Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum vesting period of outstanding options and non vested shares (in years)					4 years
Shares
Granted (in shares)	117,741
Anniversary One | Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage					33.33%
Anniversary One | Non-Executive Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage					25.00%
Anniversary Two | Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage					33.33%
Anniversary Two | Non-Executive Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage					25.00%
Anniversary Three | Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage					33.33%
Anniversary Three | Non-Executive Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage					25.00%
Anniversary Four | Non-Executive Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage					25.00%