Segment and Geographical Information - Assets and Continuing Operations by Segment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 345,385	$ 339,187	$ 331,130	$ 324,328	$ 318,222	$ 310,409	$ 303,490	$ 298,450	$ 1,340,030	$ 1,230,570	$ 1,153,772
Income (loss) from continuing operations before income taxes									275,722	245,006	266,122
Assets	10,738,114				10,329,950				10,738,114	10,329,950	10,337,877
Term Life Insurance Segment [Member]
Segment Reporting Information [Line Items]
Revenues									759,294	694,975	640,134
Income (loss) from continuing operations before income taxes									201,033	197,201	185,926
Assets	7,165,373				6,783,194				7,165,373	6,783,194	6,400,126
Investment and Savings Products Segment [Member]
Segment Reporting Information [Line Items]
Revenues									512,073	457,138	413,965
Income (loss) from continuing operations before income taxes									146,017	105,149	121,116
Assets	2,642,753				2,699,000				2,642,753	2,699,000	2,810,137
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues									68,663	78,457	99,673
Income (loss) from continuing operations before income taxes									(71,328)	(57,344)	(40,920)
Assets	$ 929,988				$ 847,756				$ 929,988	$ 847,756	$ 1,127,614