Summary of Significant Accounting Policies - Stock-Based Compensation (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	Feb. 20, 2019	Dec. 31, 2020 USD ($) offering_period $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares
Employee stock-based awards
Contractual term of awards		3 years
Stock-based compensation | $		$ 37,674	$ 35,654	$ 31,167
Stock-based compensation expense (income), net of tax | $		$ 36,584	$ 33,103	28,998
Award vesting period		3 years
Total amount of common stock reserved and available for issuance pursuant to awards granted under the 2014 Plan (in shares)		48,253,839
Employee Stock Purchase Plan
Employee stock purchase plan, shares available for grant		2,818,706
Employee stock-based awards, unrecognized compensation costs on nonvested awards | $		$ 39,056
Employee stock-based awards, weighted average recognition period		1 year 8 months 12 days
Performance Units Original Awards
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Non-vested at the beginning of the period (in shares)		1,113,691
Granted (in shares)		425,777
Vested (in shares)		(316,730)
Forfeited (in shares)		(149,529)
Non-vested at the end of the period (in shares)		1,073,209	1,113,691
Restricted Stock Units (RSUs)
Aggregate intrinsic value
Total fair value of shares or units vested | $		$ 26,492	$ 21,191	20,454
PUs Adjustment
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Non-vested at the beginning of the period (in shares)		(314,798)
Granted (in shares)		0
Vested (in shares)		0
Forfeited (in shares)		(4,710)
Non-vested at the end of the period (in shares)		(319,508)	(314,798)
Performance Shares
Employee stock-based awards
Award vesting period		3 years
Aggregate intrinsic value
Total fair value of shares or units vested | $		$ 11,812	$ 6,503	$ 3,117
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Non-vested at the beginning of the period (in shares)		798,893
Granted (in shares)		425,777
Vested (in shares)		(316,730)
Forfeited (in shares)		(154,239)
Non-vested at the end of the period (in shares)		753,701	798,893
Weighted average grant date fair value
Weighted average grant date fair value, non-vested, beginning of period (in dollars per share) | $ / shares		$ 36.56
Weighted average grant date fair value, granted (in dollars per share) | $ / shares		34.85
Weighted average grant date fair value, vested (in dollars per share) | $ / shares		37.29
Weighted average grant date fair value, forfeited (in dollars per share) | $ / shares		28.28
Weighted average grant date fair value, non-vested, end of period (in dollars per share) | $ / shares		$ 36.98	$ 36.56
Performance units disclosure
Period of anniversary from the date of grant		3
Qualifying service period	10 years	3 years
Performance Shares | Two Thousand Sixteen
Performance units disclosure
Percentage of achievement of the predefined revenue and ROIC targets		100.00%
Performance Shares | Two Thousand Seventeen
Performance units disclosure
Percentage of achievement of the predefined revenue and ROIC targets			100.00%
Performance Shares | Two Thousand Eighteen
Performance units disclosure
Percentage of achievement of the predefined revenue and ROIC targets				0.00%
Performance Shares | Revenue or revenue growth and return on invested capital
Performance units disclosure
Performance period		3
Performance Shares | Minimum | Predefined Targets Of Revenue And Return On Invested Capital Or Adjusted EBITDA
Performance units disclosure
Percentage payout rate		0.00%
Performance Shares | Minimum | Market condition associated with shareholder return of common stock
Performance units disclosure
Percentage payout rate		0.00%
Performance Shares | Maximum | Predefined Targets Of Revenue And Return On Invested Capital Or Adjusted EBITDA
Performance units disclosure
Percentage payout rate		200.00%
Performance Shares | Maximum | Market condition associated with shareholder return of common stock
Performance units disclosure
Percentage payout rate		219.00%
Employee Stock Purchase Plan
Employee Stock Purchase Plan
Employee stock purchase plan, number of offering periods | offering_period		2
Employee stock purchase plan, offering periods		6 months
Employee stock purchase plan, duration of offering periods		6
Employee stock purchase plan, maximum employee subscription rate percent		15.00%
Percentage of market price for the purchase of shares		95.00%
Employee stock purchase plan, shares issued in period		159,853	129,505	119,123
Employee stock purchase plan, shares available for grant		216,287
Three Year Vesting Option
Employee stock-based awards
Contractual term of awards		10 years
Award vesting period		3 years
Stock And Cash Incentive Plan2014
Employee stock-based awards
Total amount of common stock reserved and available for issuance pursuant to awards granted under the 2014 Plan (in shares)		12,750,000
Employee And Non Employees Stock Option
Employee stock-based awards
Weighted average fair value of options granted (in dollars per share) | $ / shares		$ 2.35	$ 3.58	$ 3.50
Weighted average assumptions used for grants
Expected volatility (as a percent)		25.40%	24.30%	25.40%
Risk-free interest rate (as a percent)		1.45%	2.47%	2.65%
Expected dividend yield (as a percent)		7.00%	7.00%	7.00%
Expected life of the option		10 years	5 years	5 years
Summary of option activity
Options outstanding balance, beginning of period (in shares)		4,835,721
Options granted (in shares)		589,993
Options exercised (in shares)		(204,540)
Options forfeited (in shares)		(151,230)
Options expired (in shares)		(337,425)
Options outstanding balance, end of period (in shares)		4,732,519	4,835,721
Options exercisable balance (in shares)		3,439,748
Options expected to vest (in shares)		1,266,640
Weighted Average Exercise Price
Weighted average exercise price, options outstanding balance beginning of period (in dollars per share) | $ / shares		$ 35.64
Weighted average exercise price, options granted (in dollars per share) | $ / shares		33.32
Weighted average exercise price, options exercised (in dollars per share) | $ / shares		24.38
Weighted average exercise price, options forfeited (in dollars per share) | $ / shares		35.36
Weighted average exercise price, options expired (in dollars per share) | $ / shares		35.82
Weighted average exercise price, options outstanding balance end of period (in dollars per share) | $ / shares		35.83	$ 35.64
Weighted average exercise price, options exercisable (in dollars per share) | $ / shares		36.40
Weighted average exercise price, options expected to vest (in dollars per share) | $ / shares		$ 34.28
Weighted average remaining contractual term
Weighted average remaining contractual term, options outstanding		6 years 3 months 7 days
Weighted average remaining contractual term, options exercisable		5 years 5 months 15 days
Weighted average remaining contractual term, options expected to vest		8 years 4 months 28 days
Aggregate intrinsic value
Aggregate intrinsic value, options outstanding | $		$ 469
Aggregate intrinsic value, options exercisable | $		469
Aggregate intrinsic value, options expected to vest | $		$ 0
Restricted Stock And Restricted Stock Units
Employee stock-based awards
Award vesting period		3 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Non-vested at the beginning of the period (in shares)		1,203,599
Granted (in shares)		1,078,124
Vested (in shares)		(792,083)
Forfeited (in shares)		(195,634)
Non-vested at the end of the period (in shares)		1,294,006	1,203,599
Weighted average grant date fair value
Weighted average grant date fair value, non-vested, beginning of period (in dollars per share) | $ / shares		$ 34.71
Weighted average grant date fair value, granted (in dollars per share) | $ / shares		31.68
Weighted average grant date fair value, vested (in dollars per share) | $ / shares		33.45
Weighted average grant date fair value, forfeited (in dollars per share) | $ / shares		34.28
Weighted average grant date fair value, non-vested, end of period (in dollars per share) | $ / shares		$ 33.02	$ 34.71
Performance Units Original Awards
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Granted (in shares)			380,856	353,507