Employee Benefit Plans - Schedule of Weighted-Average Asset Allocation by Asset Category in Partnerships in Care Pension Plan (Detail) - Pension Plan [Member] - Partnership in Care Benefits Plan [Member]	Dec. 31, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	1.30%	0.70%
Foreign Government Debt Securities [Member] | United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	15.00%	19.00%
Annuity Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	38.60%	38.60%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	25.40%	29.40%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	15.80%	9.90%
Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	3.90%	2.40%