Commitments and Contingencies - Fair Value of Annuities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Commitments And Contingencies [Line Items]
Statement value of annuities exceeding 1% of statutory surplus	$ 92,401
American General Life Insurance (A) [Member]
Commitments And Contingencies [Line Items]
Statement value of annuities exceeding 1% of statutory surplus	16,031
Pacific Life and Annuity Company (A+) [Member]
Commitments And Contingencies [Line Items]
Statement value of annuities exceeding 1% of statutory surplus	14,281
New York Life Insurance Company (A++) [Member]
Commitments And Contingencies [Line Items]
Statement value of annuities exceeding 1% of statutory surplus	12,700
Metropolitan Life Insurance Company (A+) [Member]
Commitments And Contingencies [Line Items]
Statement value of annuities exceeding 1% of statutory surplus	15,219
John Hancock Life Insurance Company USA (A+) [Member]
Commitments And Contingencies [Line Items]
Statement value of annuities exceeding 1% of statutory surplus	7,073
Athene Annuity and Life Assurance Company (B++) [Member]
Commitments And Contingencies [Line Items]
Statement value of annuities exceeding 1% of statutory surplus	6,372
Genworth Life Insurance Company (A) [Member]
Commitments And Contingencies [Line Items]
Statement value of annuities exceeding 1% of statutory surplus	4,648
Liberty Life Assurance Company of Boston (A) [Member]
Commitments And Contingencies [Line Items]
Statement value of annuities exceeding 1% of statutory surplus	4,058
Other [Member]
Commitments And Contingencies [Line Items]
Statement value of annuities exceeding 1% of statutory surplus	$ 12,019