Goodwill and Intangible Assets - Analysis of goodwill and intangible assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Goodwill
Goodwill, beginning of year	$ 249,620		$ 198,236
Goodwill, acquisitions	74,780		51,476
Goodwill, impairment	0		0
Goodwill, foreign currency translation adjustment	2,151		(92)
Goodwill, end of year	326,551		249,620	$ 198,236
Intangible assets (indefinite life)
Intangible assets with an indefinite life, beginning of year	61,874		68,174
Intangible assets with an indefinite life, acquisitions	24,431		0
Intangible assets with an indefinite life, impairment	(1,000)	[1]	(6,300)
Intangible assets with an indefinite life, foreign currency translation adjustment	605		0
Intangible assets with an indefinite life, end of year	85,910		61,874	68,174
Intangible assets (finite life)
Intangible assets with a finite life, beginning of year	323,426		386,201
Intangible assets with a finite life, acquisitions	82,482		43,000
Intangible assets with a finite life, amortization	(82,104)		(105,670)	(125,778)
Intangible assets with a finite life, foreign currency translation adjustment	1,817		(105)
Intangible assets with a finite life, impairment	0		0
Intangible assets with a finite life, end of year	325,621		323,426	386,201
Total
Goodwill and intangible assets, beginning of year	634,920		652,611
Goodwill and intangible assets, acquisitions	181,693		94,476
Goodwill and intangible assets impairment	(1,000)		(6,300)
Goodwill and intangible assets, foreign currency movements and other adjustments	4,574		(197)
Goodwill and intangible assets, end of year	738,083		634,920	652,611
Goodwill and intangible assets, gross balance					$ 1,161,336
Intangible assets with a finite life, accumulated amortization					(419,294)	$ (337,190)
Goodwill and intangible assets, accumulated foreign currency translation and other adjustments					(3,959)	(8,533)
Goodwill and intangible assets	738,083		$ 634,920	$ 652,611	738,083	634,920
Goodwill
Goodwill
Goodwill, end of year	326,551
Total
Goodwill, gross balance					331,448
Goodwill and intangible assets, accumulated foreign currency translation and other adjustments					(4,897)	$ (7,048)
Intangible assets with an indefinite life
Intangible assets (indefinite life)
Intangible assets with an indefinite life, end of year	85,910
Total
Indefinite-lived intangible assets, gross balance					85,305
Intangible assets with a finite life
Intangible assets (finite life)
Intangible assets with a finite life, end of year	$ 325,621
Total
Intangible assets with a finite life, gross balance					744,583
Intangible assets with a finite life, accumulated amortization					(419,294)
Goodwill and intangible assets, accumulated foreign currency translation and other adjustments					$ 332

[1] The impairment to the indefinite-lived intangible assets during the year ended December 31, 2019 and 2018 of $1.0 million and $6.3 million related to insurance licenses from the acquisition of UGC