Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Operating Activities
Net income	$ 151,081	$ 116,197	$ 196,565
Adjustments to reconcile income to net cash provided by operating activities:
Amortization, net of accretion	26,337	28,781	32,638
Depreciation	6,452	7,437	6,956
(Increase) decrease in cash surrender value of BOLI	(2,008)	(2,032)	(2,007)
Net realized investment (gains) losses	(34,875)	41,639	(14,654)
Share-based compensation	12,455	9,166	10,056
Deferred income taxes	8,534	(15,994)	6,795
Policy acquisition costs, net amortization (net deferral)	(2,421)	(5,598)	10
Equity in earnings (loss) of unconsolidated subsidiaries	5,762	(3,682)	(3,986)
Other	1,772	466	(4,769)
Other changes in assets and liabilities, excluding effect of business combinations:
Premiums receivable	(6,446)	(14,506)	(15,136)
Receivable from reinsurers on paid losses and loss adjustment expenses	3,803	(2,755)	3,263
Receivable from reinsurers on unpaid losses and loss adjustment expenses	(24,125)	(11,384)	27,114
Prepaid reinsurance premiums	(5,673)	(1,935)	(5,672)
Other assets	15,665	(10,458)	36,924
Reserve for losses and loss adjustment expenses	(11,898)	(52,940)	(167,747)
Unearned premiums	10,497	16,238	10,097
Reinsurance premiums payable	(113)	12,663	(26,377)
Other liabilities	14,321	(179)	5,932
Net cash provided (used) by operating activities	169,120	111,124	96,002
Purchases of:
Fixed maturities, available for sale	(636,377)	(580,577)	(645,114)
Equity securities, trading	(112,912)	(271,608)	(119,865)
Other investments	(18,613)	(33,366)	(25,109)
Funding of qualified affordable housing tax credit limited partnerships	(1,019)	(12,477)	(8,611)
Investment in unconsolidated subsidiaries	(50,890)	(61,444)	(52,295)
Proceeds from sales or maturities of:
Fixed maturities, available for sale	752,516	886,886	703,828
Equity securities, trading	85,226	236,476	134,005
Other investments	13,797	33,638	19,942
Distributions from unconsolidated subsidiaries	16,947	28,017	5,428
Net sales or maturities (purchases) of short-term investments	(322,872)	11,932	140,411
Cash received in (paid in) acquisition	0	0	35,013
Unsettled security transactions, net change	1,388	2,339	(2,953)
Funds at Lloyd's in support of Syndicate 1729, returned (deposited)	0	0	8,690
(Increase) decrease in restricted cash	0	0	78,000
Purchases of capital assets	(10,922)	(9,524)	(2,883)
Other	4,792	(2,505)	(1,507)
Net cash provided (used) by investing activities	(278,939)	227,787	266,980
Financing Activities
Borrowing under revolving credit agreement	100,000	100,000	0
Repurchase of common stock	(2,106)	(172,772)	(222,360)
External capital contribution received for segregated portfolio cells	9,952	836	0
Excess tax benefit from share-based payment arrangements	778	494	2,702
Dividends to shareholders	(118,812)	(217,626)	(71,252)
Other	(3,746)	(5,783)	(4,415)
Net cash provided (used) by financing activities	(13,934)	(294,851)	(295,325)
Increase (decrease) in cash and cash equivalents	(123,753)	44,060	67,657
Cash and cash equivalents at beginning of period	241,100	197,040	129,383
Cash and cash equivalents at end of period	117,347	241,100	197,040
Supplemental Disclosure of Cash Flow Information
Cash paid during the year for income taxes, net of refunds	(8,683)	42,784	22,968
Cash paid during the year for interest	14,732	13,996	13,408
Significant non-cash transactions
Deposit transferred as consideration for acquisition	0	0	205,244
Dividends declared and not yet paid	$ 265,659	$ 69,447	$ 167,744