Investments (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Unrealized gains and losses on fixed maturities and equity securities
Amortized Cost or Cost	$ 5,784,205		$ 5,311,457
Unrealized Gains	344,286		660,665
Unrealized Losses	118,918		9,890
Fair value of issued securities	6,009,573		5,962,232
OTTI in AOCI	2,812	[1]	3,214	[1]
Equity securities, Amortized Cost or Cost	84,754		52,396
Mortgage-backed securities [Member]
Unrealized gains and losses on fixed maturities and equity securities
Amortized Cost or Cost	555,574	[2]	547,040	[2]
Unrealized Gains	33,711	[2]	72,644	[2]
Unrealized Losses	19,560	[2]	125	[2]
Fair value of issued securities	569,725	[2]	619,559	[2]
OTTI in AOCI	0	[1],[2]	0	[1],[2]
Other including U.S. Treasury Securities [Member]
Unrealized gains and losses on fixed maturities and equity securities
Amortized Cost or Cost	449,060	[2]	371,706	[2]
Unrealized Gains	9,865	[2]	37,857	[2]
Unrealized Losses	23,351	[2]	135	[2]
Fair value of issued securities	435,574	[2]	409,428	[2]
OTTI in AOCI	0	[1],[2]	0	[1],[2]
Municipal Bonds [Member]
Unrealized gains and losses on fixed maturities and equity securities
Amortized Cost or Cost	1,425,441		1,402,424
Unrealized Gains	80,701		186,261
Unrealized Losses	34,615		2,648
Fair value of issued securities	1,471,527		1,586,037
OTTI in AOCI	0	[1]	0	[1]
Foreign government bonds [Member]
Unrealized gains and losses on fixed maturities and equity securities
Amortized Cost or Cost	50,641		48,476
Unrealized Gains	4,700		9,393
Unrealized Losses	390		0
Fair value of issued securities	54,951		57,869
OTTI in AOCI	0	[1]	0	[1]
Corporate Bonds [Member]
Unrealized gains and losses on fixed maturities and equity securities
Amortized Cost or Cost	2,457,727		2,258,554
Unrealized Gains	188,832		313,430
Unrealized Losses	32,150		4,950
Fair value of issued securities	2,614,409		2,567,034
OTTI in AOCI	0	[1]	0	[1]
Other Mortgage-backed Securities [Member]
Unrealized gains and losses on fixed maturities and equity securities
Amortized Cost or Cost	845,762		683,257
Unrealized Gains	26,477		41,080
Unrealized Losses	8,852		2,032
Fair value of issued securities	863,387		722,305
OTTI in AOCI	2,812	[1]	3,214	[1]
Equity Securities [Member]
Unrealized gains and losses on fixed maturities and equity securities
Unrealized Gains	10,723		2,397
Unrealized Losses	3,619		1,290
Fair value of issued securities	91,858		53,503
OTTI in AOCI	0	[1]	0	[1]
Equity securities, Amortized Cost or Cost	$ 84,754		$ 52,396

[1] Represents the amount of other-than-temporary impairment losses in AOCI which, beginning April 1, 2009, was not included in earnings under current accounting guidance. Amounts also include unrealized gains/(losses) on impaired securities relating to changes in the fair value of such securities subsequent to the impairment measurement date.

[2] Fair value includes securities issued by Federal National Mortgage Association (“FNMA”) of $336,193 and $375,111; Federal Home Loan Mortgage Corporation (“FHLMC”) of $427,172 and $418,174; and Government National Mortgage Association (“GNMA”) of $126,245 and $136,998 as of December 31, 2013 and 2012, respectively.