Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Fair value of annuities
Statement value of annuities exceeding 1% of statutory surplus	$ 95,912
American General Life Insurance (A) [Member]
Fair value of annuities
Statement value of annuities exceeding 1% of statutory surplus	19,930
Pacific Life and Annuity Company (A+) [Member]
Fair value of annuities
Statement value of annuities exceeding 1% of statutory surplus	15,451
New York Life Insurance Company (A++) [Member]
Fair value of annuities
Statement value of annuities exceeding 1% of statutory surplus	12,436
Metropolitan Life Insurance Company (A+) [Member]
Fair value of annuities
Statement value of annuities exceeding 1% of statutory surplus	11,826
John Hancock Life Insurance Company USA (A+) [Member]
Fair value of annuities
Statement value of annuities exceeding 1% of statutory surplus	7,370
Aviva Life Insurance Company (A) [Member]
Fair value of annuities
Statement value of annuities exceeding 1% of statutory surplus	7,085
Genworth Life Insurance Company (A) [Member]
Fair value of annuities
Statement value of annuities exceeding 1% of statutory surplus	5,246
Liberty Life Assurance Company of Boston (A) [Member]
Fair value of annuities
Statement value of annuities exceeding 1% of statutory surplus	4,733
Other [Member]
Fair value of annuities
Statement value of annuities exceeding 1% of statutory surplus	$ 11,835