Income Taxes - Provision for income taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current:
Current Federal									$ 770	$ (27,918)	$ (27,710)
Current State and local									365	1,185	(11,033)
Current Total									1,135	(26,733)	(38,743)
Tax benefits of compensation plans allocated to additional paid-in capital									7,553	6,946	13,992
Total current income tax provision									8,688	(19,787)	(24,751)
Deferred Federal									18,023	16,637	28,270
Deferred Other									1,943	3,110	3,414
Deferred Total									19,966	19,747	31,684
Deferred tax allocated to other comprehensive income									(11,669)	(9,961)	(6,093)
Total deferred income tax provision									8,297	9,786	25,591
Provision (benefit) for income taxes	$ 13,561	$ 2,148	$ 4,305	$ (3,029)	$ 620	$ (7,473)	$ (462)	$ (2,686)	$ 16,985	$ (10,001)	$ 840