Income Taxes - Income Tax Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Income Tax Expense
Expected provision at federal statutory tax rate	$ 98,843	$ 61,104	$ 42,991
State and foreign tax expense, net of federal benefit	4,695	3,726	2,255
Interest and dividend on preferred stock	0	0	710
Meals and entertainment	772	649	469
Fines and penalties	134	84	(36)
Federal credits	(58)	(182)	(103)
Adjustment to deferred tax assets and liabilities	(54)	(3)	(3)
Other	1,160	746	100
Total income tax expense (benefit)	$ 105,492	$ 66,124	$ 46,383