Related Party Transactions - Revenue and Expense Reimbursements from Related Parties (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
The Canada Life Assurance Company (CLAC), Great-West Life, and Putnam
Related Party Transaction [Line Items]
Receives corporate support services	[1],[2],[3]	$ 22,400	$ 18,763	$ 12,609
Putnam
Related Party Transaction [Line Items]
Provides shareholder services	[1]	16,598	15,852	5,531
Receives reimbursement from tax sharing indemnification related to state and local tax liabilities	[1]	9,611	12,261	13,563
Entities Affiliated to Subsidiaries
Related Party Transaction [Line Items]
Investment Advisory Fees	[4]	$ 150,441	$ 140,455	$ 138,936

[1] A wholly-owned subsidiary of Lifeco U.S.

[2] An indirect wholly-owned subsidiary of Lifeco

[3] An indirect wholly-owned subsidiary of Lifeco U.S.

[4] Great-West Capital Management, LLC, a subsidiary of the Company, serves as a Registered Investment Advisor to Great-West Funds, an open-end management investment company, which is an affiliate of GWL&A and to Great-West Trust Company, LLC, an affiliated trust company. Great-West Trust Company, LLC, serves as trustee to several collective investment trusts. The Company provides Great-West Funds, Inc. recordkeeping and administrative services to shareholders and account owners.