Employee Benefit Plans - Plan Assets Measured and Reported in Financial Statements at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 431,747	$ 401,929
U.S. government and U.S. government agency securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,196	8,803
U.S. corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	57,669	45,714
International corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14,088	13,034
Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	74,750	610
Money market funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	618	303
Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14,952	7,964
Insurance buy-in policy
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31,281	29,857
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	618	913
Level 1 | U.S. government and U.S. government agency securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 | U.S. corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 | International corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	610
Level 1 | Money market funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	618	303
Level 1 | Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 | Insurance buy-in policy
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	102,905	75,515
Level 2 | U.S. government and U.S. government agency securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,196	8,803
Level 2 | U.S. corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	57,669	45,714
Level 2 | International corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14,088	13,034
Level 2 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 | Money market funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 | Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14,952	7,964
Level 2 | Insurance buy-in policy
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31,281	29,857
Level 3 | U.S. government and U.S. government agency securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | U.S. corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | International corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Money market funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Insurance buy-in policy
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31,281	29,857
Fair Value Measured at Net Asset Value Per Share [Member] | Collective trust funds, U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	78,170	69,699
Fair Value Measured at Net Asset Value Per Share [Member] | Collective trust funds, International equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	89,381	176,103
Fair Value Measured at Net Asset Value Per Share [Member] | Collective trust funds, International fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15,387	14,752
Fair Value Measured at Net Asset Value Per Share [Member] | Collective trust funds, diversified funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 39,255	$ 35,090