Summary of Significant Accounting Policies - Stock-Based Compensation (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) offering_period $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares
Employee stock-based awards
Contractual term of awards	3 years
Stock-based compensation | $	$ 35,654	$ 31,167	$ 30,019
Stock-based compensation expense (income), net of tax | $	$ 33,103	$ 28,998	$ 26,512
Stock-based compensation expense per basic and diluted share (in dollars per share) | $ / shares	$ 0.12	$ 0.10	$ 0.10
Certain options as a percentage of total outstanding options	100.00%
Total amount of shares of common stock reserved and available for issuance pursuant to awards granted under the 2014 Plan (in shares)	48,253,839
Summary of option activity
Options outstanding balance, end of period (in shares)	4,835,721
Employee Stock Purchase Plan
Employee stock purchase plan, shares available for grant	4,095,067
Employee stock-based awards, unrecognized compensation costs on nonvested awards | $	$ 39,696
Employee stock-based awards, weighted average recognition period	1 year 9 months 18 days
Tranche Two
Employee stock-based awards
Certain options as a percentage of total outstanding options	3.00%
Summary of option activity
Options outstanding balance, end of period (in shares)	144,400
Tranche One
Employee stock-based awards
Certain options as a percentage of total outstanding options	97.00%
Summary of option activity
Options outstanding balance, end of period (in shares)	4,691,321
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)	967,049
Granted (in shares)	380,856
Vested (in shares)	(206,279)
Forfeited (in shares)	(27,935)
Non-vested at the end of the period (in shares)	1,113,691	967,049
Restricted Stock Units (RSUs)
Dividends accrued and paid
Accrued cash dividends | $	$ 3,215	$ 2,899	$ 2,590
Cash dividends paid | $	2,369	2,477	2,370
Total fair value of shares or units vested | $	$ 21,191	$ 20,454	19,825
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)	(299,948)
Granted (in shares)	0
Vested (in shares)	0
Forfeited (in shares)	(14,850)
Non-vested at the end of the period (in shares)	(314,798)	(299,948)
Performance Shares
Dividends accrued and paid
Accrued cash dividends | $	$ 2,260	$ 1,804	1,290
Cash dividends paid | $	1,162	644	205
Total fair value of shares or units vested | $	$ 6,503	$ 3,117	$ 1,242
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Non-vested at the beginning of the period (in shares)	667,101
Granted (in shares)	380,856
Vested (in shares)	(206,279)
Forfeited (in shares)	(42,785)
Non-vested at the end of the period (in shares)	798,893	667,101
Weighted average grant date fair value
Weighted average grant date fair value, non-vested, beginning of period (in dollars per share) | $ / shares	$ 36.54
Weighted average grant date fair value, granted (in dollars per share) | $ / shares	36.07
Weighted average grant date fair value, vested (in dollars per share) | $ / shares	37.97
Weighted average grant date fair value, forfeited (in dollars per share) | $ / shares	26.50
Weighted average grant date fair value, non-vested, end of period (in dollars per share) | $ / shares	$ 36.56	$ 36.54
Performance units disclosure
Period of anniversary from the date of grant	3 years
Qualifying age for grant of performance units	55 years
Qualifying service period	10 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		50.00%
Performance Shares | Two Thousand Eighteen
Performance units disclosure
Percentage of achievement of the predefined revenue and ROIC targets			100.00%
Performance Shares | Revenue or revenue growth and return on invested capital
Performance units disclosure
Performance period	3 years
Performance Shares | Market condition associated with shareholder return of common stock
Performance units disclosure
Performance period	3 years
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	200.00%
Employee Stock Purchase Plan
Employee Stock Purchase Plan
Employee stock purchase plan, number of offering periods | offering_period	2
Employee stock purchase plan, duration of offering periods	6 months
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	129,505	119,123	102,826
Employee stock purchase plan, shares available for grant	376,140
Three Year Vesting Option
Employee stock-based awards
Contractual term of awards	10 years
Award vesting period	3 years
Five Year Vesting Option
Employee stock-based awards
Contractual term of awards	10 years
Award vesting period	5 years
Stock And Cash Incentive Plan2014
Employee stock-based awards
Total amount of shares 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	$ 3.58	$ 3.50	$ 4.28
Weighted average assumptions used for grants
Expected volatility (as a percent)	24.30%	25.40%	25.70%
Risk-free interest rate (as a percent)	2.47%	2.65%	1.96%
Expected dividend yield (as a percent)	7.00%	7.00%	6.00%
Expected life of the option	5 years	5 years	5 years
Summary of option activity
Options outstanding balance, beginning of period (in shares)	4,271,834
Options granted (in shares)	920,706
Options exercised (in shares)	(303,543)
Options forfeited (in shares)	(23,984)
Options expired (in shares)	(29,292)
Options outstanding balance, end of period (in shares)	4,835,721	4,271,834
Options exercisable balance (in shares)	3,068,945
Options expected to vest (in shares)	1,648,127
Weighted Average Exercise Price
Weighted average exercise price, options outstanding balance beginning of period (in dollars per share) | $ / shares	$ 34.78
Weighted average exercise price, options granted (in dollars per share) | $ / shares	35.71
Weighted average exercise price, options exercised (in dollars per share) | $ / shares	23.86
Weighted average exercise price, options forfeited (in dollars per share) | $ / shares	35.21
Weighted average exercise price, options expired (in dollars per share) | $ / shares	34.78
Weighted average exercise price, options outstanding balance end of period (in dollars per share) | $ / shares	35.64	$ 34.78
Weighted average exercise price, options exercisable (in dollars per share) | $ / shares	35.80
Weighted average exercise price, options expected to vest (in dollars per share) | $ / shares	$ 35.34
Weighted average remaining contractual term
Weighted average remaining contractual term, options outstanding	6 years 8 months 19 days
Weighted average remaining contractual term, options exercisable	5 years 9 months 21 days
Weighted average remaining contractual term, options expected to vest	8 years 5 months 19 days
Aggregate intrinsic value
Aggregate intrinsic value, options outstanding | $	$ 3,005
Aggregate intrinsic value, options exercisable | $	3,005
Aggregate intrinsic value, options expected to vest | $	0
Aggregate intrinsic value of stock options exercised
Aggregate intrinsic value of stock options exercised | $	$ 3,148	$ 2,181	$ 8,485
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)	1,196,566
Granted (in shares)	823,508
Vested (in shares)	(678,138)
Forfeited (in shares)	(138,337)
Non-vested at the end of the period (in shares)	1,203,599	1,196,566
Weighted average grant date fair value
Weighted average grant date fair value, non-vested, beginning of period (in dollars per share) | $ / shares	$ 34.33
Weighted average grant date fair value, granted (in dollars per share) | $ / shares	34.72
Weighted average grant date fair value, vested (in dollars per share) | $ / shares	34.06
Weighted average grant date fair value, forfeited (in dollars per share) | $ / shares	34.75
Weighted average grant date fair value, non-vested, end of period (in dollars per share) | $ / shares	$ 34.71	$ 34.33
Performance Units Original Awards
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Granted (in shares)		353,507	229,692