Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Available for sale
Fixed maturity securities - available for sale	$ 6,610,368	$ 6,022,473
Equity securities - available for sale, at fair value	296,352	517,466
Short-term investments*	258,186us-gaap_ShortTermInvestments	178,753us-gaap_ShortTermInvestments
Restricted cash and securities	2,729hcc_RestrictedCashHeldAtFairValue	1,853hcc_RestrictedCashHeldAtFairValue
Premium, claims and other receivables	56,493hcc_PremiumClaimsAndOtherAtFairValue	66,515hcc_PremiumClaimsAndOtherAtFairValue
Other assets	1,324	961
Total assets measured at fair value	7,225,452hcc_TotalAssetsMeasuredAtFairValue	6,788,021hcc_TotalAssetsMeasuredAtFairValue
Notes payable	875,094us-gaap_NotesPayableFairValueDisclosure	707,656us-gaap_NotesPayableFairValueDisclosure
Accounts payable and accrued liabilities - earnout liabilities	11,473hcc_EarnoutLiabilityFairValue	9,112hcc_EarnoutLiabilityFairValue
Total liabilities measured at fair value	886,567us-gaap_LiabilitiesFairValueDisclosure	716,768us-gaap_LiabilitiesFairValueDisclosure
Fair Value, Inputs, Level 1 [Member]
Available for sale
Fixed maturity securities - available for sale	63,663	84,032
Equity securities - available for sale, at fair value	296,352	517,466
Short-term investments*	159,297	68,958
Restricted cash and securities	0	0
Premium, claims and other receivables	0	0
Other assets	18	20
Total assets measured at fair value	519,330	670,476
Notes payable	0	0
Accounts payable and accrued liabilities - earnout liabilities	0	0
Total liabilities measured at fair value	0	0
Fair Value, Inputs, Level 2 [Member]
Available for sale
Fixed maturity securities - available for sale	6,546,557	5,929,024
Equity securities - available for sale, at fair value	0	0
Short-term investments*	98,889	109,795
Restricted cash and securities	2,729	1,853
Premium, claims and other receivables	56,493	66,515
Other assets	0	0
Total assets measured at fair value	6,704,668	6,107,187
Notes payable	875,094	707,656
Accounts payable and accrued liabilities - earnout liabilities	2,729	1,853
Total liabilities measured at fair value	877,823	709,509
Fair Value, Inputs, Level 3 [Member]
Available for sale
Fixed maturity securities - available for sale	148	9,417
Equity securities - available for sale, at fair value	0	0
Short-term investments*	0	0
Restricted cash and securities	0	0
Premium, claims and other receivables	0	0
Other assets	1,306	941
Total assets measured at fair value	1,454	10,358
Notes payable	0	0
Accounts payable and accrued liabilities - earnout liabilities	8,744	7,259
Total liabilities measured at fair value	8,744	7,259
US Government and Government Agency Securities [Member]
Available for sale
Fixed maturity securities - available for sale	70,969	92,709
US Government and Government Agency Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available for sale
Fixed maturity securities - available for sale	63,663	84,032
US Government and Government Agency Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available for sale
Fixed maturity securities - available for sale	7,306	8,677
US Government and Government Agency Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Fixed Maturity Securities of States, Municipalities and Political Subdivisions Securities [Member]
Available for sale
Fixed maturity securities - available for sale	954,708	986,486
Fixed Maturity Securities of States, Municipalities and Political Subdivisions Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Fixed Maturity Securities of States, Municipalities and Political Subdivisions Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available for sale
Fixed maturity securities - available for sale	954,708	986,486
Fixed Maturity Securities of States, Municipalities and Political Subdivisions Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Special Purpose Revenue Bonds Of States Municipalities And Political Subdivisions [Member]
Available for sale
Fixed maturity securities - available for sale	2,389,012	2,265,195
Special Purpose Revenue Bonds Of States Municipalities And Political Subdivisions [Member] \| Fair Value, Inputs, Level 1 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Special Purpose Revenue Bonds Of States Municipalities And Political Subdivisions [Member] \| Fair Value, Inputs, Level 2 [Member]
Available for sale
Fixed maturity securities - available for sale	2,389,012	2,255,928
Special Purpose Revenue Bonds Of States Municipalities And Political Subdivisions [Member] \| Fair Value, Inputs, Level 3 [Member]
Available for sale
Fixed maturity securities - available for sale	0	9,267
Corporate Securities [Member]
Available for sale
Fixed maturity securities - available for sale	1,276,835	1,225,238
Corporate Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Corporate Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available for sale
Fixed maturity securities - available for sale	1,276,687	1,225,088
Corporate Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available for sale
Fixed maturity securities - available for sale	148	150
Residential Mortgage Backed Securities [Member]
Available for sale
Fixed maturity securities - available for sale	821,694	618,119
Residential Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Residential Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available for sale
Fixed maturity securities - available for sale	821,694	618,119
Residential Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Commercial Mortgage Backed Securities [Member]
Available for sale
Fixed maturity securities - available for sale	611,631	504,888
Commercial Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Commercial Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available for sale
Fixed maturity securities - available for sale	611,631	504,888
Commercial Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Asset-backed Securities [Member]
Available for sale
Fixed maturity securities - available for sale	366,827	182,392
Asset-backed Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Asset-backed Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available for sale
Fixed maturity securities - available for sale	366,827	182,392
Asset-backed Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Foreign Government Securities [Member]
Available for sale
Fixed maturity securities - available for sale	118,692	147,446
Foreign Government Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available for sale
Fixed maturity securities - available for sale	0	0
Foreign Government Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available for sale
Fixed maturity securities - available for sale	118,692	147,446
Foreign Government Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available for sale
Fixed maturity securities - available for sale	$ 0	$ 0

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Amount of debt securities categorized neither as held-to-maturity nor trading.

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Fair value of financial and nonfinancial obligations.

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