Borrowings - Long-Term Borrowings (Details) $ in Thousands, ¥ in Billions			3 Months Ended		6 Months Ended
	Jun. 16, 2017 USD ($)	Apr. 15, 2015	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 JPY (¥) item	Jun. 30, 2017 USD ($) item	Dec. 31, 2016 USD ($)	Oct. 31, 2016	Jul. 25, 2016 JPY (¥)	Jul. 25, 2016 USD ($)
Long-Term Borrowings
Discount								$ 1,437	$ 956
Outstanding principal amount								1,681,142
Interest expense			$ 8,720	$ 7,075	$ 15,548	$ 14,176
Deferred financing fees								51,382	4,012
Reconciliation of senior secured credit facility
Outstanding principal								1,681,142
Net deferred financing fees								(51,382)	(4,012)
Discount								(1,437)	(956)
Long term borrowings								1,628,323	564,957
Aggregate future required minimum principal payments based on the terms of loan
2018								115,000
2019								115,000
2020 and thereafter								1,451,142
Total principal of long-term borrowings								1,681,142
Broker-Dealer Credit Facility on committed basis
Long-Term Borrowings
Maximum borrowing capacity								75,000
Broker-Dealer Credit Facility on committed basis | Base rate
Long-Term Borrowings
Interest rate added to variable rate (as a percent)		1.25%
Broker-Dealer Credit Facility on committed basis | LIBOR rate
Long-Term Borrowings
Interest rate added to variable rate (as a percent)					1.25%
Senior Secured Second Lien Notes
Long-Term Borrowings
Face amount	$ 500,000
Interest rate (as a percent)	6.75%
Percentage of the voting stock of the entity's domestic subsidiaries' direct foreign subsidiaries as collateral					65.00%
Outstanding principal amount								500,000
Interest period	6 months
Reconciliation of senior secured credit facility
Outstanding principal								500,000
Long term borrowings								474,639
Aggregate future required minimum principal payments based on the terms of loan
Total principal of long-term borrowings								500,000
Senior Secured Second Lien Notes | Restricted Cash
Long-Term Borrowings
Face amount								500,000
Escrow Credit Facility
Long-Term Borrowings
Face amount								$ 610,000
Annual amortization obligation as a percentage of original principal amount							7.50%	7.50%
Escrow Credit Facility | Restricted Cash
Long-Term Borrowings
Face amount								$ 610,000
Senior Secured Credit Facility
Long-Term Borrowings
Face amount								540,000
Outstanding principal amount								1,150,000	540,000
Reconciliation of senior secured credit facility
Outstanding principal								1,150,000	540,000
Long term borrowings								1,122,602	535,104
Aggregate future required minimum principal payments based on the terms of loan
Total principal of long-term borrowings								$ 1,150,000	540,000
Senior Secured Credit Facility Fourth Amendment
Long-Term Borrowings
Number of anniversaries of closing of the acquisition | item							4	4
Annual amortization obligation as a percentage of original principal amount							7.50%	7.50%
Outstanding principal amount								$ 1,150,000
Reconciliation of senior secured credit facility
Outstanding principal								1,150,000
Aggregate future required minimum principal payments based on the terms of loan
Total principal of long-term borrowings								1,150,000
Senior Secured Credit Facility Fourth Amendment | Maximum
Long-Term Borrowings
Leverage ratio					5.00%
interest coverage ratio					3.00%
Senior Secured Credit Facility Fourth Amendment | Minimum
Long-Term Borrowings
interest coverage ratio					2.75%
Senior Secured Credit Facility Fourth Amendment | From and after the fiscal quarter ending March 31, 2019 [Member]
Long-Term Borrowings
Leverage ratio					4.25%
Senior Secured Credit Facility Fourth Amendment | From and after the fiscal quarter ending March 31, 2020 [Member]
Long-Term Borrowings
Leverage ratio					3.50%
Senior Secured Credit Facility Fourth Amendment | From the fiscal quarter ending March 31,2021 and thereafter [Member]
Long-Term Borrowings
Leverage ratio					3.25%
SBI Bonds
Long-Term Borrowings
Loss due to change in currency rates			$ 1,500		$ 1,200
Outstanding principal amount								31,142	29,925
Reconciliation of senior secured credit facility
Outstanding principal								31,142	29,925
Long term borrowings								31,082	29,853
Aggregate future required minimum principal payments based on the terms of loan
Total principal of long-term borrowings								31,142	$ 29,925
VFH
Long-Term Borrowings
Percentage of the non-voting stock of the entity's domestic subsidiaries' direct foreign subsidiaries collateralized					100.00%
VFH | Maximum
Long-Term Borrowings
Percentage of the voting stock of the entity's domestic subsidiaries' direct foreign subsidiaries as collateral					65.00%
VFH | Senior Secured Credit Facility
Long-Term Borrowings
Face amount								$ 100,000
VFH | Senior Secured Credit Facility Fourth Amendment | Term Loan | Prime rate
Long-Term Borrowings
Interest rate (as a percent)							2.75%	2.75%
Interest rate added to variable rate (as a percent)					2.00%
VFH | Senior Secured Credit Facility Fourth Amendment | Term Loan | Federal funds effective rate
Long-Term Borrowings
Interest rate added to variable rate (as a percent)					0.50%
VFH | Senior Secured Credit Facility Fourth Amendment | Term Loan | Eurodollar
Long-Term Borrowings
Interest rate added to variable rate (as a percent)					1.00%
VFH | Senior Secured Credit Facility Fourth Amendment | Term Loan | LIBOR rate
Long-Term Borrowings
Interest rate (as a percent)							3.75%	3.75%
Interest rate added to variable rate (as a percent)					1.00%
VFH | Senior Secured Credit Facility Fourth Amendment | Revolving credit facility | Prime rate
Long-Term Borrowings
Interest rate (as a percent)							2.00%	2.00%
Interest rate added to variable rate (as a percent)					1.00%
VFH | Senior Secured Credit Facility Fourth Amendment | Revolving credit facility | Federal funds effective rate
Long-Term Borrowings
Interest rate added to variable rate (as a percent)					0.50%
VFH | Senior Secured Credit Facility Fourth Amendment | Revolving credit facility | Eurodollar
Long-Term Borrowings
Interest rate added to variable rate (as a percent)					1.00%
VFH | Senior Secured Credit Facility Fourth Amendment | Revolving credit facility | LIBOR rate
Long-Term Borrowings
Interest rate (as a percent)							3.00%	3.00%
Interest rate added to variable rate (as a percent)					0.00%
VFH | SBI Bonds
Long-Term Borrowings
Face amount							¥ 3.5	$ 31,100			¥ 3.5	$ 33,100
Interest rate (as a percent)										5.00%	4.00%	4.00%