Equity method investment - Financial Position and Results of Operations (Details) - Bankers Healthcare Group, LLC - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Assets	$ 1,156,130		$ 840,398
Liabilities	942,372		641,037
Equity interests	213,758		199,361
Total liabilities and equity	1,156,130		$ 840,398
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenues	97,943	$ 62,817
Net income	$ 32,471	$ 27,135

The amount of assets reported by an equity method investment of the entity.

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Amount of equity, including noncontrolling interest, reported by an equity method investment of the entity.

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Amount of income (loss) from continuing operations reported by an equity method investee.

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The amount of liabilities reported by an equity method investment of the entity.

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Amount of revenue from sale of product and rendering of service reported by equity method investee.

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