Long-term Equity-based Compensation - Narrative (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) installment $ / shares shares	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares) | shares	10,000,000
Shares available for grant (in shares) | shares	3,254,822
Share-based compensation expense	$ 25,300	$ 18,600	$ 9,400
Total compensation cost not yet recognized	$ 20,400
Annual awards of deferred stock units to be issued to each non-employee director, aggregate fair value		$ 110	$ 110
Weighted-average grant-date fair values (in dollars per share) | $ / shares	$ 20.99	$ 15.14	$ 8.89
Total intrinsic value	$ 7,700	$ 3,900	$ 4,900
Cash received from exercises of awards	2,400	900	4,000
Total tax benefit realized for tax deductions from exercise of awards	$ 1,600	800	1,700
Total fair value of DSUs that vested during the years		1,000	900
Performance Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reduction in share authorization if maximum performance level is met or exceeded (in shares) | shares	1,082,460
Award vesting period	3 years
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting installments | installment	3
Award vesting period	3 years
Expiration period	10 years
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual awards of restricted stock units to be issued to each non-employee director, aggregate fair value	$ 130
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of vested awards	24,800	8,700	3,200
Tax benefits for tax deductions realized from awards	$ 5,200	$ 1,800	$ 1,100
Performance Period 1 | Performance Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reduction in share authorization if maximum performance level is met or exceeded (in shares) | shares	438,402
Number of additional shares to be granted if maximum performance level is met or exceeded (in shares) | shares	146,134
Performance Period 2 | Performance Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reduction in share authorization if maximum performance level is met or exceeded (in shares) | shares	412,029
Number of additional shares to be granted if maximum performance level is met or exceeded (in shares) | shares	137,343
Performance Period 3 | Performance Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reduction in share authorization if maximum performance level is met or exceeded (in shares) | shares	232,029
Number of additional shares to be granted if maximum performance level is met or exceeded (in shares) | shares	77,343