Capital Structure - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) ClassOfCommonStock $ / shares shares	Sep. 30, 2018 USD ($) $ / shares shares	Feb. 28, 2017 USD ($)	Dec. 30, 2014 USD ($)
Equity, Class of Treasury Stock [Line Items]
Number of classes of common stock outstanding | ClassOfCommonStock			1
Acquisition of restricted stock from employees in connection with withholding tax payments (in shares) | shares	0	0	22,666	45,646
Withholding tax payments related to the vesting of restricted stock for total consideration			$ 1,408,000	$ 2,790,000
Weighted average purchase price prior to the vesting date (in dollars per share) | $ / shares			$ 62.11	$ 61.12
2014 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock authorized, maximum						$ 20,000,000
2017 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Additional authorized amount					$ 100,000,000
Authorized increase in repurchase amount, 2018					40,000,000
Common stock purchased under the repurchase program (in shares) | shares	125,744	155,837	563,769	503,019
Common stock aggregate purchase price including commissions	$ 8,346,000	$ 9,657,000	$ 34,476,000	$ 30,003,000
Common stock average purchase price per share (in dollars per share) | $ / shares	$ 66.38	$ 61.97	$ 61.15	$ 59.65
2017 Repurchase Program | Minimum
Equity, Class of Treasury Stock [Line Items]
Authorized increase in repurchase amount					20,000,000
2017 Repurchase Program | Maximum
Equity, Class of Treasury Stock [Line Items]
Authorized increase in repurchase amount					$ 40,000,000