SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (INVESTMENT BORROWINGS) (Details)	1 Months Ended	12 Months Ended
	Dec. 31, 2013 subsidiary	Dec. 31, 2016 USD ($) subsidiary	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Number of insurance subsidiaries | subsidiary	2	3
Investment borrowings		$ 1,647,400,000	$ 1,548,100,000
Repurchase agreements, borrowings outstanding		0	0
Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Federal home loan bank stock		71,200,000
Investment borrowings		1,647,400,000
Fair value of collateral for borrowings		2,000,000,000
Aggregate fee to prepay all fixed rate FHLB borrowings		2,600,000
Interest expense on FHLB borrowings		17,500,000	$ 10,900,000	$ 18,700,000
Borrowings due January 2018 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		Jan. 31, 2018
Interest rate		1.226%
Borrowings due January 2018 rate two [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		Jan. 31, 2018
Interest rate		1.222%
Borrowings due February 2018 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		Feb. 28, 2018
Interest rate		1.191%
Borrowings due February 2018 rate two [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		Feb. 28, 2018
Interest rate		1.001%
Borrowings due February 2018 rate three [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 22,000,000
Maturity date		Feb. 28, 2018
Interest rate		1.267%
Borrowings due May 2018 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 100,000,000
Maturity date		May 30, 2018
Interest rate		1.206%
Borrowings due July 2018 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		Jul. 31, 2018
Interest rate		1.36%
Borrowings due August 2018 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		Aug. 31, 2018
Interest rate		1.022%
Borrowings due December 2018 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 10,000,000
Maturity date		Dec. 31, 2018
Interest rate		1.266%
Borrowings due January 2019 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		Jan. 31, 2019
Interest rate		1.30%
Borrowings due February 2019 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		Feb. 28, 2019
Interest rate		1.001%
Borrowings due March 2019 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 100,000,000
Maturity date		Mar. 31, 2019
Interest rate		1.216%
Borrowings due July 2019 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 21,800,000
Maturity date		Jul. 31, 2019
Interest rate		1.234%
Borrowings due October 2019 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 15,000,000
Maturity date		Oct. 31, 2019
Interest rate		1.399%
Borrowing due May 2020 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		May 31, 2020
Interest rate		1.224%
Borrowings due June 2020 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 21,800,000
Maturity date		Jun. 30, 2020
Interest rate		1.96%
Borrowing due September 2020, Rate One [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 25,000,000
Maturity date		Sep. 30, 2020
Interest rate		1.622%
Borrowings due September 2020, Rate Two [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 100,000,000
Maturity date		Sep. 30, 2020
Interest rate		1.416%
Borrowings due September 2020, Rate Three [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		Sep. 30, 2020
Interest rate		1.416%
Borrowings due September 2020, Rate Four [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 75,000,000
Maturity date		Sep. 30, 2020
Interest rate		1.118%
Borrowings due October 2020 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 100,000,000
Maturity date		Oct. 31, 2020
Interest rate		1.109%
Borrowings due December 2020 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		Dec. 31, 2020
Interest rate		1.335%
Borrowings Due July 2021 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 100,000,000
Maturity date		Jul. 31, 2021
Interest rate		1.431%
Borrowings due July 2021 Rate Two [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 57,700,000
Maturity date		Jul. 31, 2021
Interest rate		1.411%
Borrowings Due August 2021, Rate One [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 100,000,000
Maturity date		Aug. 31, 2021
Interest rate		1.40%
Borrowings Due August 2021, Rate Two [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Maturity date		Aug. 31, 2021
Interest rate		2.55%
Borrowings Due August 2021, Rate Two [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 28,200,000
Borrowings Due August 2021, Rate Three [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 125,000,000
Maturity date		Aug. 31, 2021
Interest rate		1.236%
Borrowings Due September 2021 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 50,000,000
Maturity date		Sep. 30, 2021
Interest rate		1.477%
Borrowings due March 2023 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 25,400,000
Maturity date		Mar. 31, 2023
Interest rate		2.16%
Borrowings due June 2025 [Member] | Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment borrowings		$ 20,500,000
Maturity date		Jun. 30, 2025
Interest rate		2.94%