Qualified Employee Benefit Plans - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) investment	Dec. 31, 2017 USD ($) investment	Dec. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Contributions to qualified profit sharing plan	$ 15,000	$ 14,400	$ 14,300
Defined contribution expense for foreign entities	7,100	$ 6,800	6,800
Other comprehensive (loss) gain	$ 1,471
Liability Hedging Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	20.00%
Retirement plan, number of investments | investment	3
Return Seeking Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	27.00%
Risk Mitigating Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	14.00%
Diversifying Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	21.00%
Dynamic Asset Allocation
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	18.00%
Fixed Income Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Retirement plan, number of investments | investment	2	2
Equity mutual fund
Defined Benefit Plan Disclosure [Line Items]
Retirement plan, number of investments | investment	7	3
U.S. Based Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Retirement plan, number of investments | investment	4
Non-U.S. Based Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Retirement plan, number of investments | investment	3
Equity Private Investment Trusts
Defined Benefit Plan Disclosure [Line Items]
Retirement plan, number of investments | investment	1	2
Collective Investment Trust
Defined Benefit Plan Disclosure [Line Items]
Retirement plan, number of investments | investment	1
Minimum | Liability Hedging Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	10.00%
Minimum | Return Seeking Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	15.00%
Minimum | Risk Mitigating Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	5.00%
Minimum | Diversifying Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	10.00%
Minimum | Dynamic Asset Allocation
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	5.00%
Maximum | Liability Hedging Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	35.00%
Maximum | Return Seeking Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	40.00%
Maximum | Risk Mitigating Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	35.00%
Maximum | Diversifying Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	35.00%
Maximum | Dynamic Asset Allocation
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations, percent	35.00%
Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	$ 5,000	$ 4,000
Estimated employer contributions in 2019	4,000
Other comprehensive (loss) gain	1,687	(3,068)	(3,032)
Discount rate and lump sum interest rates	(9,700)	11,900	3,500
Changes in census data	(200)	(1,400)
Earnings of plan assets exceeding expectations	(9,200)	(8,500)	(1,800)
Mortality assumption	$ (400)	700	$ 1,700
Defined benefit plan, amortization period	31 years 7 months 13 days
Future amortization of prior service cost	$ 24
Loss to be amortized over next fiscal year	1,100	1,100
Accumulated benefit obligation	$ 116,200	$ 125,200
Assumptions used calculating benefit obligation, discount rate, percent	4.40%	3.90%
Expected long-term rate of return on plan assets	5.75%	6.00%	6.50%