Summary of Quantitative Inputs and Assumptions for Items Categorized in Level III of Fair Value Hierarchy (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 4,358,240	$ 4,024,612
Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	1,154,820	1,192,227
Discounted Cash Flows | Loans and Receivables | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 222,726	$ 241,897
Discounted Cash Flows | Loans and Receivables | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	12.20%	11.00%
Discounted Cash Flows | Loans and Receivables | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	6.80%	6.70%
Discounted Cash Flows | Loans and Receivables | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	24.80%	20.60%
Transaction Price Valuation Technique | Loans and Receivables | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 47,514
Third Party Pricing Valuation Technique | Loans and Receivables | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 17,618	$ 20,097
Equity Securities | Discounted Cash Flows | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	13.10%	13.60%
Revenue CAGR	8.10%	10.20%
Exit Multiple - EBITDA	9.6	9.6
Exit Multiple - P/E	11.3	11.2
Exit Capitalization Rate	8.90%	9.00%
Equity Securities | Market Comparable Companies | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
EBITDA Multiple		6.6
Partnership And LLC Interests | Discounted Cash Flows | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	9.50%	9.30%
Revenue CAGR	8.40%	8.60%
Exit Multiple - EBITDA	10.3	9.8
Exit Capitalization Rate	6.40%	6.30%
Debt Instruments | Discounted Cash Flows | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	14.40%	14.10%
Exit Capitalization Rate	5.30%	5.80%
Assets Of Consolidated CLO Vehicles | Market Comparable Companies | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
EBITDA Multiple	7.2	6.5
Blackstone's Treasury Cash Management Strategies | Discounted Cash Flows
Fair Value, Option, Quantitative Disclosures [Line Items]
Reinvestment Rate		4.00%
Recovery Lag	12 months	12 months
Pre-payment Rate	20.00%	20.00%
Blackstone's Treasury Cash Management Strategies | Discounted Cash Flows | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 15,663	$ 32,004
Blackstone's Treasury Cash Management Strategies | Discounted Cash Flows | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	9.50%	8.60%
Default Rate	1.90%	1.90%
Reinvestment Rate	3.94%
Exit Multiple - EBITDA	69.40%	67.00%
Blackstone's Treasury Cash Management Strategies | Discounted Cash Flows | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	8.40%	5.80%
Default Rate	1.00%	1.00%
Reinvestment Rate	3.50%
Exit Multiple - EBITDA	30.00%	30.00%
Blackstone's Treasury Cash Management Strategies | Discounted Cash Flows | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	13.50%	14.00%
Default Rate	2.00%	2.00%
Reinvestment Rate	4.00%
Exit Multiple - EBITDA	70.00%	70.00%
Blackstone's Treasury Cash Management Strategies | Third Party Pricing Valuation Technique | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 15,192	$ 22,653
Other | Discounted Cash Flows
Fair Value, Option, Quantitative Disclosures [Line Items]
Default Rate	2.00%	2.00%
Reinvestment Rate	4.00%	4.00%
Recovery Lag	12 months	12 months
Exit Multiple - EBITDA	70.00%	70.00%
Pre-payment Rate	20.00%	20.00%
Other | Discounted Cash Flows | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 83,210	$ 81,984
Other | Discounted Cash Flows | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	3.90%	3.30%
Other | Discounted Cash Flows | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	1.70%	1.40%
Other | Discounted Cash Flows | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	19.70%	12.50%
Other | Transaction Price Valuation Technique | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 16,199	$ 19,200
Investments Of Consolidated Blackstone Funds | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	736,698	774,392
Investments Of Consolidated Blackstone Funds | Equity Securities | Discounted Cash Flows | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 69,289	$ 66,962
Investments Of Consolidated Blackstone Funds | Equity Securities | Discounted Cash Flows | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	7.40%	7.80%
Revenue CAGR	(1.50%)	(5.00%)
Exit Multiple - EBITDA	4	5
Exit Multiple - P/E	10.5	10.5
Exit Capitalization Rate	5.50%	550.00%
Investments Of Consolidated Blackstone Funds | Equity Securities | Discounted Cash Flows | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	25.00%	25.00%
Revenue CAGR	20.20%	61.50%
Exit Multiple - EBITDA	18.2	18.2
Exit Multiple - P/E	17	17
Exit Capitalization Rate	11.40%	1140.00%
Investments Of Consolidated Blackstone Funds | Equity Securities | Market Comparable Companies
Fair Value, Option, Quantitative Disclosures [Line Items]
Book Value Multiple	0.9	9
Investments Of Consolidated Blackstone Funds | Equity Securities | Market Comparable Companies | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 1,661	$ 1,710
Investments Of Consolidated Blackstone Funds | Equity Securities | Market Comparable Companies | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
EBITDA Multiple		6.5
Investments Of Consolidated Blackstone Funds | Equity Securities | Market Comparable Companies | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
EBITDA Multiple		8
Investments Of Consolidated Blackstone Funds | Equity Securities | Transaction Price Valuation Technique
Fair Value, Option, Quantitative Disclosures [Line Items]
EBITDA Multiple	6.1
Investments Of Consolidated Blackstone Funds | Equity Securities | Transaction Price Valuation Technique | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 5,869	$ 6,722
Investments Of Consolidated Blackstone Funds | Equity Securities | Other | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	5,878	5,426
Investments Of Consolidated Blackstone Funds | Equity Securities | Third Party Pricing Valuation Technique | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 27	$ 29
Investments Of Consolidated Blackstone Funds | Partnership And LLC Interests | Discounted Cash Flows
Fair Value, Option, Quantitative Disclosures [Line Items]
Exit Multiple - P/E	9.3	9.3
Investments Of Consolidated Blackstone Funds | Partnership And LLC Interests | Discounted Cash Flows | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 413,719	$ 423,588
Investments Of Consolidated Blackstone Funds | Partnership And LLC Interests | Discounted Cash Flows | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	2.10%	2.10%
Revenue CAGR	(13.80%)	(24.10%)
Exit Multiple - EBITDA	0.1	0.1
Exit Capitalization Rate	300.00%	2.70%
Investments Of Consolidated Blackstone Funds | Partnership And LLC Interests | Discounted Cash Flows | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	29.20%	25.80%
Revenue CAGR	67.10%	31.80%
Exit Multiple - EBITDA	23.5	23.8
Exit Capitalization Rate	1210.00%	12.10%
Investments Of Consolidated Blackstone Funds | Partnership And LLC Interests | Transaction Price Valuation Technique | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 9,671	$ 30,437
Investments Of Consolidated Blackstone Funds | Partnership And LLC Interests | Other | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	7,965	1,403
Investments Of Consolidated Blackstone Funds | Partnership And LLC Interests | Third Party Pricing Valuation Technique | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 14,342	$ 16,963
Investments Of Consolidated Blackstone Funds | Debt Instruments | Discounted Cash Flows
Fair Value, Option, Quantitative Disclosures [Line Items]
Revenue CAGR	6.80%	16.80%
Exit Multiple - EBITDA	1200.00%
Exit Multiple - EBITDA		12
Investments Of Consolidated Blackstone Funds | Debt Instruments | Discounted Cash Flows | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 4,071	$ 4,086
Investments Of Consolidated Blackstone Funds | Debt Instruments | Discounted Cash Flows | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	8.30%	6.50%
Exit Capitalization Rate	1.00%	1.00%
Investments Of Consolidated Blackstone Funds | Debt Instruments | Discounted Cash Flows | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Discount Rate	52.70%	52.70%
Exit Capitalization Rate	8.30%	8.30%
Investments Of Consolidated Blackstone Funds | Debt Instruments | Transaction Price Valuation Technique | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 386	$ 78
Investments Of Consolidated Blackstone Funds | Debt Instruments | Third Party Pricing Valuation Technique | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	14,794	16,217
Investments Of Consolidated Blackstone Funds | Assets Of Consolidated CLO Vehicles | Market Comparable Companies | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 16,584	$ 19,783
Investments Of Consolidated Blackstone Funds | Assets Of Consolidated CLO Vehicles | Market Comparable Companies | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
EBITDA Multiple	4.0	4.5
Investments Of Consolidated Blackstone Funds | Assets Of Consolidated CLO Vehicles | Market Comparable Companies | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
EBITDA Multiple	15.0	7
Investments Of Consolidated Blackstone Funds | Assets Of Consolidated CLO Vehicles | Third Party Pricing Valuation Technique | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value assets	$ 172,442	$ 180,988